<PAGE>

    As filed with the Securities and Exchange Commission on January 28, 2000
                                                 Registration No. 333-
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                               -------------------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933
                               -------------------

                                   ARIBA, INC.
             (Exact name of registrant as specified in its charter)

<TABLE>

<S>                                 <C>                            <C>
            DELAWARE                            7372                   77-0439730
  (State or other jurisdiction      (Primary Standard Industrial      (IRS Employer
of incorporation or organization)    Classification Code Number)   Identification No.)
</TABLE>

                              1565 CHARLESTON ROAD
                         MOUNTAIN VIEW, CALIFORNIA 94043
                                 (650) 930-6200
               (Address of principal executive offices) (Zip Code)
                               -------------------

                        TRADING DYNAMICS 1998 STOCK PLAN
                        TRADING DYNAMICS 1999 STOCK PLAN
                            (Full title of the Plans)
                               -------------------

                                EDWARD P. KINSEY
       CHIEF FINANCIAL OFFICER, VICE PRESIDENT FINANCE AND ADMINISTRATION
                                   ARIBA, INC.
                              1565 CHARLESTON ROAD
                         MOUNTAIN VIEW, CALIFORNIA 94043

                     (Name and address of agent for service)
                                 (650) 930-6200
          (Telephone number, including area code, of agent for service)
                               -------------------

<TABLE>
<CAPTION>

                         CALCULATION OF REGISTRATION FEE
-----------------------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------

            Title of                                           Proposed Maximum      Proposed Maximum
           Securities                      Amount                  Offering              Aggregate                Amount of
              to be                        to be                     Price               Offering               Registration
           Registered                    Registered (1)            per Share             Price (2)                   Fee
           ----------                    ----------                ---------             -----                       ---
<S>                                      <C>                   <C>                   <C>                        <C>
TRADING DYNAMICS 1998 STOCK PLAN
     Options                                488,964                   N/A                   N/A                       N/A
     Common Stock (par value $.002)      488,964 shares            $10.2194(2)       $ 4,996,918.702(2)           $1,319.187

TRADING DYNAMICS 1999 STOCK PLAN
     Options                                514,991                   N/A                   N/A                       N/A
     Common Stock (par value $.002)      514,991 shares            $44.8474(2)       $23,096,007.37(2)            $6,097.346
</TABLE>


<PAGE>

(1)      This Registration Statement shall also cover any additional shares of
         Common Stock which become issuable under the Trading Dynamics 1998
         Stock Plan and Trading Dynamics 1999 Stock Plan by reason of any stock
         dividend, stock split, recapitalization or other similar transaction
         effected without the receipt of consideration which results in an
         increase in the number of the outstanding shares of Common Stock of
         Ariba, Inc.

(2)      Calculated solely for purposes of this offering under Rule 457(h) of
         the Securities Act of 1933, as amended, on the basis of the weighted
         average exercise price of the outstanding options.


<PAGE>

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

         Ariba, Inc. (the "Registrant") hereby incorporates by reference into
this Registration Statement the following documents previously filed with the
Securities and Exchange Commission (the "SEC"):

(a)      The Registrant's Annual Report on Form 10-K for the fiscal year ended
         September 30, 1999;

(b)      The Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
         ended December 31, 1999; and

(c)      The Registrant's Report on Form 8-K filed January 25, 2000; and

(d)      The Registrant's Registration Statement No. 000-26299 on Form 8-A filed
         with the SEC on January 8, 1999, together with all amendments thereto,
         pursuant to Section 12 of the Securities Exchange Act of 1934, as
         amended (the "1934 Act") in which there is described the terms, rights
         and provisions applicable to the Registrant's outstanding Common Stock.

         All reports and definitive proxy or information statements filed
pursuant to Section 13(a), 13(c), 14 or 15(d) of the 1934 Act after the date of
this Registration Statement and prior to the filing of a post-effective
amendment which indicates that all securities offered hereby have been sold or
which deregisters all securities then remaining unsold shall be deemed to be
incorporated by reference into this Registration Statement and to be a part
hereof from the date of filing of such documents.

ITEM 4.  DESCRIPTION OF SECURITIES

         Not Applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL

         Not Applicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Section 145 of the Delaware General Corporation Law authorizes a court
to award or a corporation's board of directors to grant indemnification to
directors and officers in terms sufficiently broad to permit such
indemnification under certain circumstances for liabilities (including
reimbursement for expenses incurred) arising under the 1933 Act. Article VII,
Section 6, of the Registrant's Bylaws provides for mandatory indemnification of
its directors and officers and permissible indemnification of employees and
other agents to the maximum extent permitted by the Delaware General Corporation
Law. The Registrant's Certificate of Incorporation provides that, pursuant to
Delaware law, its directors shall not be liable for monetary damages for breach
of their fiduciary duty as directors to the Registrant and its stockholders.
This provision in the Certificate of Incorporation does not eliminate the
fiduciary duty of the directors, and, in appropriate circumstances, equitable
remedies such as injunctive or other forms of non-monetary relief will remain
available under Delaware law. In addition, each director will continue to be
subject to liability for breach of the director's duty of loyalty to the
Registrant for acts or omissions not in good faith or involving intentional
misconduct, for knowing violations of law, for actions leading to improper
personal benefit to the director and for payment of dividends or approval of
stock repurchases or redemptions that are unlawful under Delaware law. The
provision also does not affect a director's responsibilities under any other
law, such as the federal securities laws or state or federal environmental laws.
The Registrant has entered into Indemnification Agreements with its officers and
directors. The Indemnification Agreements provide the Registrant's officers and
directors with further indemnification to the maximum extent permitted by the
Delaware General Corporation Law.


                                     II-1

<PAGE>

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not Applicable.

ITEM 8.  EXHIBITS

<TABLE>
<CAPTION>
Exhibit Number    Exhibit
--------------    -------
<S>               <C>
      4           Instrument Defining Rights of Stockholders. Reference is made
                  to Registrant's Registration Statement No. 000-26299 on Form
                  8-A, together with all amendments thereto, which is
                  incorporated herein by reference pursuant to Item 3(d) of this
                  Registration Statement.

      5           Opinion and consent of Gunderson Dettmer Stough Villeneuve
                  Franklin & Hachigian, LLP.

    23.1          Consent of KPMG LLP, Independent Auditors.

    23.2          Consent of Gunderson Dettmer Stough Villeneuve Franklin &
                  Hachigian, LLP is contained in Exhibit 5.

    24            Power of Attorney. Reference is made to page II-5 of this
                  Registration Statement.
</TABLE>

ITEM 9.  UNDERTAKINGS

             A.   The undersigned Registrant hereby undertakes: (1) to file,
during any period in which offers or sales are being made, a post-effective
amendment to this Registration Statement (i) to include any prospectus required
by Section 10(a)(3) of the 1933 Act, (ii) to reflect in the prospectus any facts
or events arising after the effective date of this Registration Statement (or
the most recent post-effective amendment thereof) which, individually or in the
aggregate, represent a fundamental change in the information set forth in this
Registration Statement and (iii) to include any material information with
respect to the plan of distribution not previously disclosed in this
Registration Statement or any material change to such information in this
Registration Statement; PROVIDED, however, that clauses (1)(i) and (1)(ii) shall
not apply if the information required to be included in a post-effective
amendment by those paragraphs is contained in periodic reports filed with or
furnished to the SEC by the Registrant pursuant to Section 13 or Section 15(d)
of the 1934 Act that are incorporated by reference in this Registration
Statement; (2) that for the purpose of determining any liability under the 1933
Act each such post-effective amendment shall be deemed to be a new registration
statement relating to the securities offered therein and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof and (3) to remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the Registrant's Trading Dynamics 1998 Stock Plan and Trading
Dynamics 1999 Stock Plan.

             B.   The undersigned Registrant hereby undertakes that, for
purposes of determining any liability under the 1933 Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
1934 Act that is incorporated by reference in this Registration Statement shall
be deemed to be a new registration statement relating to the securities offered
therein, and the offering of such securities at that time shall be deemed to be
the initial bona fide offering thereof.

             C.   Insofar as indemnification for liabilities arising under
the 1933 Act may be permitted to directors, officers or controlling persons of
the Registrant pursuant to the indemnification provisions summarized in Item 6
or otherwise, the Registrant has been advised that, in the opinion of the SEC,
such indemnification is against public policy as expressed in the 1933 Act, and
is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer or controlling person of the Registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the 1933 Act and will be governed by the final
adjudication of such issue.


                                     II-2

<PAGE>

                                   SIGNATURES


                  Pursuant to the requirements of the Securities Act of 1933,
as amended, the Registrant certifies that it has reasonable grounds to
believe that it meets all of the requirements for filing on Form S-8 and has
duly caused this Registration Statement to be signed on its behalf by the
undersigned, thereunto duly authorized, in the City of Mountain View, State
of California on this 27th day of January, 2000.

                                 ARIBA, INC.


                                 By:      /s/ Keith J. Krach
                                          -------------------------------------
                                          Keith J. Krach
                                          President and Chief Executive Officer


                                POWER OF ATTORNEY


KNOW ALL PERSONS BY THESE PRESENTS:

                  That the undersigned officers and directors of Ariba, Inc., a
Delaware corporation, do hereby constitute and appoint Keith J. Krach and Edward
P. Kinsey, and either of them, the lawful attorneys-in-fact and agents with full
power and authority to do any and all acts and things and to execute any and all
instruments which said attorneys and agents, and either one of them, determine
may be necessary or advisable or required to enable said corporation to comply
with the Securities Act of 1933, as amended, and any rules or regulations or
requirements of the Securities and Exchange Commission in connection with this
Registration Statement. Without limiting the generality of the foregoing power
and authority, the powers granted include the power and authority to sign the
names of the undersigned officers and directors in the capacities indicated
below to this Registration Statement, to any and all amendments, both
pre-effective and post-effective, and supplements to this Registration
Statement, and to any and all instruments or documents filed as part of or in
conjunction with this Registration Statement or amendments or supplements
thereof, and each of the undersigned hereby ratifies and confirms all that said
attorneys and agents, or either one of them, shall do or cause to be done by
virtue hereof. This Power of Attorney may be signed in several counterparts.

                  IN WITNESS WHEREOF, each of the undersigned has executed this
Power of Attorney as of the date indicated.

                  Pursuant to the requirements of the Securities Act of 1933, as
amended, this Registration Statement has been signed below by the following
persons in the capacities and on the dates indicated.

<TABLE>
<CAPTION>

Signature                                 Title                                               Date
---------                                 -----                                               ----
<S>                                       <C>                                                 <C>
   /s/ Keith J. Krach
-------------------------------------     President, Chief Executive Officer and Director     January 27, 2000
             Keith J. Krach               (Principal Executive Officer)

   /s/ Edward P. Kinsey
-------------------------------------     Chief Financial Officer Vice President-Finance and  January 27, 2000
            Edward P. Kinsey              Administration (Principal Financial and Accounting
                                          Officer) and Secretary

<PAGE>

<CAPTION>
Signature                                 Title                                               Date
---------                                 -----                                               ----
<S>                                       <C>                                                 <C>

     /s/ Robert C. Kagle
-------------------------------------     Director                                            January 27, 2000
             Robert C. Kagle

     /s/ Paul Hegarty
-------------------------------------     Director                                            January 27, 2000
              Paul Hegarty

     /s/ John B. Mumford
-------------------------------------     Director                                            January 27, 2000
             John B. Mumford

     /s/ Hatim A. Tyabji
-------------------------------------     Director                                            January 27, 2000
             Hatim A. Tyabji
</TABLE>

<PAGE>

                                  EXHIBIT INDEX

<TABLE>
<CAPTION>
Exhibit Number    Exhibit
--------------    -------
<S>               <C>
     4            Instrument Defining Rights of Stockholders. Reference is made
                  to Registrant's Registration Statement No. 000-26299 on Form
                  8-A, together with all amendments thereto, which is
                  incorporated herein by reference pursuant to Item 3(d) of this
                  Registration Statement.

     5            Opinion and consent of Gunderson Dettmer Stough Villeneuve
                  Franklin & Hachigian, LLP.

    23.1          Consent of KPMG LLP, Independent Accountants.

    23.2          Consent of Gunderson Dettmer Stough Villeneuve Franklin &
                  Hachigian, LLP is contained in Exhibit 5.

    24            Power of Attorney. Reference is made to page II-5 of this
                  Registration Statement.
</TABLE>
[{"type": "S-8", "sequence": "1", "description": "S-8", "secsgml_size_bytes": 18122}]
{"company-data": {"conformed-name": "ARIBA INC", "cik": "0001084755", "assigned-sic": "7372", "irs-number": "770439730", "state-of-incorporation": "DE", "fiscal-year-end": "0930"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-95665", "film-number": "516770"}, "business-address": {"street1": "1565 CHARLESTON RD", "city": "MOUNTAIN VIEW", "state": "CA", "zip": "94043", "phone": "6509306200"}, "mail-address": {"street1": "1565 CHARLESTON RD", "city": "MOUNTAIN VIEW", "state": "CA", "zip": "94043"}}
As filed with the Securities and Exchange Commission on January 28, 2000
                                                 Registration No. 333-
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                               -------------------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933
                               -------------------

                                   ARIBA, INC.
             (Exact name of registrant as specified in its charter)
DELAWARE                            7372                   77-0439730
  (State or other jurisdiction      (Primary Standard Industrial      (IRS Employer
of incorporation or organization)    Classification Code Number)   Identification No.)
1565 CHARLESTON ROAD
                         MOUNTAIN VIEW, CALIFORNIA 94043
                                 (650) 930-6200
               (Address of principal executive offices) (Zip Code)
                               -------------------

                        TRADING DYNAMICS 1998 STOCK PLAN
                        TRADING DYNAMICS 1999 STOCK PLAN
                            (Full title of the Plans)
                               -------------------

                                EDWARD P. KINSEY
       CHIEF FINANCIAL OFFICER, VICE PRESIDENT FINANCE AND ADMINISTRATION
                                   ARIBA, INC.
                              1565 CHARLESTON ROAD
                         MOUNTAIN VIEW, CALIFORNIA 94043

                     (Name and address of agent for service)
                                 (650) 930-6200
          (Telephone number, including area code, of agent for service)
                               -------------------
CALCULATION OF REGISTRATION FEE
-----------------------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------

            Title of                                           Proposed Maximum      Proposed Maximum
           Securities                      Amount                  Offering              Aggregate                Amount of
              to be                        to be                     Price               Offering               Registration
           Registered                    Registered (1)            per Share             Price (2)                   Fee
           ----------                    ----------                ---------             -----                       ---
TRADING DYNAMICS 1998 STOCK PLAN
     Options                                488,964                   N/A                   N/A                       N/A
     Common Stock (par value $.002)      488,964 shares            $10.2194(2)       $ 4,996,918.702(2)           $1,319.187

TRADING DYNAMICS 1999 STOCK PLAN
     Options                                514,991                   N/A                   N/A                       N/A
     Common Stock (par value $.002)      514,991 shares            $44.8474(2)       $23,096,007.37(2)            $6,097.346
(1)      This Registration Statement shall also cover any additional shares of
         Common Stock which become issuable under the Trading Dynamics 1998
         Stock Plan and Trading Dynamics 1999 Stock Plan by reason of any stock
         dividend, stock split, recapitalization or other similar transaction
         effected without the receipt of consideration which results in an
         increase in the number of the outstanding shares of Common Stock of
         Ariba, Inc.

(2)      Calculated solely for purposes of this offering under Rule 457(h) of
         the Securities Act of 1933, as amended, on the basis of the weighted
         average exercise price of the outstanding options.
PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

         Ariba, Inc. (the "Registrant") hereby incorporates by reference into
this Registration Statement the following documents previously filed with the
Securities and Exchange Commission (the "SEC"):

(a)      The Registrant's Annual Report on Form 10-K for the fiscal year ended
         September 30, 1999;

(b)      The Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
         ended December 31, 1999; and

(c)      The Registrant's Report on Form 8-K filed January 25, 2000; and

(d)      The Registrant's Registration Statement No. 000-26299 on Form 8-A filed
         with the SEC on January 8, 1999, together with all amendments thereto,
         pursuant to Section 12 of the Securities Exchange Act of 1934, as
         amended (the "1934 Act") in which there is described the terms, rights
         and provisions applicable to the Registrant's outstanding Common Stock.

         All reports and definitive proxy or information statements filed
pursuant to Section 13(a), 13(c), 14 or 15(d) of the 1934 Act after the date of
this Registration Statement and prior to the filing of a post-effective
amendment which indicates that all securities offered hereby have been sold or
which deregisters all securities then remaining unsold shall be deemed to be
incorporated by reference into this Registration Statement and to be a part
hereof from the date of filing of such documents.

ITEM 4.  DESCRIPTION OF SECURITIES

         Not Applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL

         Not Applicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Section 145 of the Delaware General Corporation Law authorizes a court
to award or a corporation's board of directors to grant indemnification to
directors and officers in terms sufficiently broad to permit such
indemnification under certain circumstances for liabilities (including
reimbursement for expenses incurred) arising under the 1933 Act. Article VII,
Section 6, of the Registrant's Bylaws provides for mandatory indemnification of
its directors and officers and permissible indemnification of employees and
other agents to the maximum extent permitted by the Delaware General Corporation
Law. The Registrant's Certificate of Incorporation provides that, pursuant to
Delaware law, its directors shall not be liable for monetary damages for breach
of their fiduciary duty as directors to the Registrant and its stockholders.
This provision in the Certificate of Incorporation does not eliminate the
fiduciary duty of the directors, and, in appropriate circumstances, equitable
remedies such as injunctive or other forms of non-monetary relief will remain
available under Delaware law. In addition, each director will continue to be
subject to liability for breach of the director's duty of loyalty to the
Registrant for acts or omissions not in good faith or involving intentional
misconduct, for knowing violations of law, for actions leading to improper
personal benefit to the director and for payment of dividends or approval of
stock repurchases or redemptions that are unlawful under Delaware law. The
provision also does not affect a director's responsibilities under any other
law, such as the federal securities laws or state or federal environmental laws.
The Registrant has entered into Indemnification Agreements with its officers and
directors. The Indemnification Agreements provide the Registrant's officers and
directors with further indemnification to the maximum extent permitted by the
Delaware General Corporation Law.

                                     II-1
ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not Applicable.

ITEM 8.  EXHIBITS
Exhibit Number    Exhibit
--------------    -------
4           Instrument Defining Rights of Stockholders. Reference is made
                  to Registrant's Registration Statement No. 000-26299 on Form
                  8-A, together with all amendments thereto, which is
                  incorporated herein by reference pursuant to Item 3(d) of this
                  Registration Statement.

      5           Opinion and consent of Gunderson Dettmer Stough Villeneuve
                  Franklin & Hachigian, LLP.

    23.1          Consent of KPMG LLP, Independent Auditors.

    23.2          Consent of Gunderson Dettmer Stough Villeneuve Franklin &
                  Hachigian, LLP is contained in Exhibit 5.

    24            Power of Attorney. Reference is made to page II-5 of this
                  Registration Statement.
ITEM 9.  UNDERTAKINGS

             A.   The undersigned Registrant hereby undertakes: (1) to file,
during any period in which offers or sales are being made, a post-effective
amendment to this Registration Statement (i) to include any prospectus required
by Section 10(a)(3) of the 1933 Act, (ii) to reflect in the prospectus any facts
or events arising after the effective date of this Registration Statement (or
the most recent post-effective amendment thereof) which, individually or in the
aggregate, represent a fundamental change in the information set forth in this
Registration Statement and (iii) to include any material information with
respect to the plan of distribution not previously disclosed in this
Registration Statement or any material change to such information in this
Registration Statement; PROVIDED, however, that clauses (1)(i) and (1)(ii) shall
not apply if the information required to be included in a post-effective
amendment by those paragraphs is contained in periodic reports filed with or
furnished to the SEC by the Registrant pursuant to Section 13 or Section 15(d)
of the 1934 Act that are incorporated by reference in this Registration
Statement; (2) that for the purpose of determining any liability under the 1933
Act each such post-effective amendment shall be deemed to be a new registration
statement relating to the securities offered therein and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof and (3) to remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the Registrant's Trading Dynamics 1998 Stock Plan and Trading
Dynamics 1999 Stock Plan.

             B.   The undersigned Registrant hereby undertakes that, for
purposes of determining any liability under the 1933 Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
1934 Act that is incorporated by reference in this Registration Statement shall
be deemed to be a new registration statement relating to the securities offered
therein, and the offering of such securities at that time shall be deemed to be
the initial bona fide offering thereof.

             C.   Insofar as indemnification for liabilities arising under
the 1933 Act may be permitted to directors, officers or controlling persons of
the Registrant pursuant to the indemnification provisions summarized in Item 6
or otherwise, the Registrant has been advised that, in the opinion of the SEC,
such indemnification is against public policy as expressed in the 1933 Act, and
is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer or controlling person of the Registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the 1933 Act and will be governed by the final
adjudication of such issue.

                                     II-2
SIGNATURES

                  Pursuant to the requirements of the Securities Act of 1933,
as amended, the Registrant certifies that it has reasonable grounds to
believe that it meets all of the requirements for filing on Form S-8 and has
duly caused this Registration Statement to be signed on its behalf by the
undersigned, thereunto duly authorized, in the City of Mountain View, State
of California on this 27th day of January, 2000.

                                 ARIBA, INC.

                                 By:      /s/ Keith J. Krach
                                          -------------------------------------
                                          Keith J. Krach
                                          President and Chief Executive Officer

                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

                  That the undersigned officers and directors of Ariba, Inc., a
Delaware corporation, do hereby constitute and appoint Keith J. Krach and Edward
P. Kinsey, and either of them, the lawful attorneys-in-fact and agents with full
power and authority to do any and all acts and things and to execute any and all
instruments which said attorneys and agents, and either one of them, determine
may be necessary or advisable or required to enable said corporation to comply
with the Securities Act of 1933, as amended, and any rules or regulations or
requirements of the Securities and Exchange Commission in connection with this
Registration Statement. Without limiting the generality of the foregoing power
and authority, the powers granted include the power and authority to sign the
names of the undersigned officers and directors in the capacities indicated
below to this Registration Statement, to any and all amendments, both
pre-effective and post-effective, and supplements to this Registration
Statement, and to any and all instruments or documents filed as part of or in
conjunction with this Registration Statement or amendments or supplements
thereof, and each of the undersigned hereby ratifies and confirms all that said
attorneys and agents, or either one of them, shall do or cause to be done by
virtue hereof. This Power of Attorney may be signed in several counterparts.

                  IN WITNESS WHEREOF, each of the undersigned has executed this
Power of Attorney as of the date indicated.

                  Pursuant to the requirements of the Securities Act of 1933, as
amended, this Registration Statement has been signed below by the following
persons in the capacities and on the dates indicated.
Signature                                 Title                                               Date
---------                                 -----                                               ----
/s/ Keith J. Krach
-------------------------------------     President, Chief Executive Officer and Director     January 27, 2000
             Keith J. Krach               (Principal Executive Officer)

   /s/ Edward P. Kinsey
-------------------------------------     Chief Financial Officer Vice President-Finance and  January 27, 2000
            Edward P. Kinsey              Administration (Principal Financial and Accounting
                                          Officer) and Secretary
Signature                                 Title                                               Date
---------                                 -----                                               ----
/s/ Robert C. Kagle
-------------------------------------     Director                                            January 27, 2000
             Robert C. Kagle

     /s/ Paul Hegarty
-------------------------------------     Director                                            January 27, 2000
              Paul Hegarty

     /s/ John B. Mumford
-------------------------------------     Director                                            January 27, 2000
             John B. Mumford

     /s/ Hatim A. Tyabji
-------------------------------------     Director                                            January 27, 2000
             Hatim A. Tyabji
EXHIBIT INDEX
Exhibit Number    Exhibit
--------------    -------
4            Instrument Defining Rights of Stockholders. Reference is made
                  to Registrant's Registration Statement No. 000-26299 on Form
                  8-A, together with all amendments thereto, which is
                  incorporated herein by reference pursuant to Item 3(d) of this
                  Registration Statement.

     5            Opinion and consent of Gunderson Dettmer Stough Villeneuve
                  Franklin & Hachigian, LLP.

    23.1          Consent of KPMG LLP, Independent Accountants.

    23.2          Consent of Gunderson Dettmer Stough Villeneuve Franklin &
                  Hachigian, LLP is contained in Exhibit 5.

    24            Power of Attorney. Reference is made to page II-5 of this
                  Registration Statement.