Document:

<PAGE>   1
                                                                   EXHIBIT 10.13

$109,915.08                                              Incline Village, Nevada
                                                                  April 30, 2000

     FOR VALUE RECEIVED, the undersigned, Collaboration Properties, Inc., a
Nevada corporation ("Borrower") promises to pay to the order of William L.
Campbell ("Lender"), in lawful money of the United States of America and in
immediately available funds at the principal office of Lender, or its
successor, or at such other location as Lender, or any subsequent holder hereof
shall designate in writing, the aggregate unpaid principal amount of all
advances ("Advances") set forth on Exhibit A as well as all Advances made
hereafter by Lender to Borrower under the terms of this Secured Nonrecourse
Revolving Promissory Note (this "Note"), up to a maximum principal amount of
One Hundred Nine Thousand Nine Hundred Fifteen Dollars and Eight Cents
($109,915.08) plus interest as set forth on Exhibit A. This Note hereby amends
and restates any loan agreements previously entered into between Borrower and
Lender and still outstanding as of the date hereof. This Note shall also amend
and restate and loan agreements previously entered into between VCT, Inc., a
Nevada corporation, which merged into Borrower as of April 21, 2000 ("VCT") and
Lender. This Note evidences outstanding obligations and is being issued in
substitution for, and not in payment of, that certain Amended and Restated
Secured Nonrecourse Revolving Promissory Note dated November 18, 1999, as
amended, made by Borrower in favor of Lender and [certain demand notes] between
VCT and Lender. Interest shall accrue on the aggregate unpaid principal amount
of such Advances at an interest rate equal to the lesser of 10% per annum or
the maximum rate allowed by law on the first business day of each month after
an Advance has been made and shall be payable annually in arrears; provided
that any interest not paid on any annual payment date shall be added to
principal and thereafter shall accrue interest along with the principal.
Interest shall be computed on a 365 day year based upon the actual number of
days elapsed. The entire principal amount and all accrued but unpaid interest
shall be due and payable upon the earlier of (i) three years from the date
hereof; (ii) the date of consummation of a transaction in which more than 50%
of Borrower is not owned by persons who were holders of capital stock or
securities convertible into capital stock of Borrower immediately prior to such
transaction or in which the composition of a majority of the Board of Directors
of Borrower changes; or (iii) 180 days following a firmly underwritten initial
public offering of Borrower at an aggregate offering price to the public of at
least $5,000,000 and with an offering price to the public of at least $2.50 per
share. This Note shall be terminated and canceled promptly upon Borrower's
repayment of the principal amount and all accrued but unpaid interest.

     This Note is subject to prepayment upon ninety (90) days written notice,
without penalty. Lender may waive this prepayment notice requirement in
Lender's sole and absolute discretion.

     Borrower represents and warrants that it is duly organized, legally
existing, in good standing and authorized to enter into this Note and that this
Note constitutes the legal, valid and binding obligation of Borrower.

     Borrower irrevocably waives the right to direct the application of any and
all payments at any time hereafter received by Lender from or on behalf of
Borrower, and Borrower irrevocably agrees that Lender shall have the continuing
exclusive right to apply any and all such payments against the then due and
owing obligations of Borrower as Lender may deem advisable. In the absence of a
specific determination by Lender with respect thereto, all payments shall be
applied in the following order:
<PAGE>   2
(a) then due and payable fees and expenses; (b) then due and payable interest
payments and mandatory prepayments; and (c) then due and payable principal
payments and optional prepayments.

     Lender is hereby authorized by Borrower to endorse on Lender's books and
records each Advance made by Lender under this Note and the amount of each
payment or prepayment of principal of each such Advance received by Lender. It
is understood, however, that failure to make any such endorsement (or any errors
in notation) shall not affect the obligations of Borrower with respect to
Advances made hereunder, and payments of principal and interest by Borrower
shall be credited to Borrower notwithstanding the failure to make a notation (or
any errors in notations) thereof on such books and records.

     If Borrower shall fail to do or to perform all things required of Borrower
in this Note within the time provided herein (such failure being an "Event of
Default"), Lender or any other holder of this Note, by negotiation, assignment
or otherwise, may, at Lender's sole option, accelerate the maturity of the Note
and the obligation evidenced hereby shall become due and payable in full upon
written notice of such acceleration to Borrower. The failure to pay interest on
any annual payment date shall not constitute an Event of Default hereunder, and
such accrued and unpaid interest shall be added to principal as set forth above.

     Borrower promises to pay Lender all reasonable costs and reasonable
expenses of collection of this Note and to pay all reasonable attorneys' fees
incurred in such collection or in any suit or action to collect this Note or in
any appeal thereof. Borrower waives presentment, demand, protest, notice of
protest, notice of dishonor, notice of nonpayment, and any and all other notices
and demands in connection with the delivery, acceptance, performance, default or
enforcement of this Note, as well as any applicable statute of limitations. No
delay by Lender in exercising any power or right hereunder shall operate as a
waiver of any power or right. Time is of the essence as to all obligations
hereunder.

     Payment of this Note is limited to payment out of the assets of Borrower
which secure the repayment of this Note, and no stockholder of Borrower shall be
personally liable for the payment of this Note.

     This Note shall be deemed to be made under, and shall be construed in
accordance with and governed by, the laws of the State of Nevada, excluding
conflicts of laws principles.

                                        COLLABORATION PROPERTIES, INC.

                                        By: /s/ [Signature Illegible]
                                           ------------------------------------
                                        Title:   Secretary
                                           ------------------------------------

<PAGE>   3

                                   EXHIBIT A

                     Schedule of Advances and Interest for
                 Secured Nonrecourse Revolving Promissory Note
                              As of April 30, 2000
<PAGE>   4
CPI Notes Payable
Consolidated Note effective 4/30/00

As of:                          04/30/00

<TABLE>
<CAPTION>
                                                          Principal         Total
          Note                   Date      Principal     Outstanding       Interest
                                Issued       Amount        04/30/00        04/30/00
<S>                            <C>       <C>            <C>             <C>
William L. Campbell (WLC)
     Total of Notes            03/31/00     109,915.08     109,915.08        5,570.10
     Interest calc             04/30/00           0.00           0.00          949.19

                                         $  109,915.08  $  109,915.08   $    6,519.29

                                         TOTAL PRINCIPAL + INTEREST =   $  116,434.37
</TABLE>

                                                                   Page: 1 of: 1<PAGE>   1
                                                                   EXHIBIT 10.14

                         COLLABORATION PROPERTIES, INC.

                   SERIES A PREFERRED STOCK PURCHASE AGREEMENT

                                DECEMBER 9, 1999

<PAGE>   2

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                PAGE
                                                                                                ----
<S>     <C>                                                                                     <C>
SECTION 1 Authorization and Sale of Series A Preferred Stock.....................................1

        1.1    Authorization.....................................................................1
        1.2    Sale of Series A Preferred........................................................1

SECTION 2 Closing Date; Delivery.................................................................1

        2.1    Closing Date......................................................................1
        2.2    Delivery..........................................................................1

SECTION 3 Representations and Warranties of the Company..........................................2

        3.1    Corporate Organization and Authority..............................................2
        3.2    Capitalization....................................................................2
        3.3    Subsidiaries......................................................................3
        3.4    Authorization.....................................................................3
        3.5    Validity of Shares................................................................3
        3.6    No Conflict with Other Instruments................................................3
        3.7    Litigation........................................................................3
        3.8    Title to Properties, Liens and Encumbrances.......................................4
        3.9    Patents and Other Propriety Rights................................................4
        3.10   Company's Contracts...............................................................5
        3.11   No Defaults, Violations or Conflicts..............................................5
        3.12   Private Offering..................................................................5
        3.13   Prior Registration Rights.........................................................5
        3.14   Full Disclosure...................................................................5
        3.15   Related-Party Transactions........................................................6
        3.16   Distributions.....................................................................6
        3.17   Employee Compensation Plans.......................................................6
        3.18   Employee Relations................................................................6
        3.19   Brokers and Finders...............................................................6
        3.20   Transactions with Affiliates......................................................6
        3.21   Governmental Consents.............................................................6
        3.22   Environmental Regulations.........................................................7
        3.23   Minute Books......................................................................7
        3.24   Financial Statements..............................................................7
        3.25   Absence of Certain Changes........................................................7
</TABLE>

                                      -i-
<PAGE>   3

                               TABLE OF CONTENTS
                                  (CONTINUED)

<TABLE>
<CAPTION>
                                                                                                PAGE
                                                                                                ----
<S>     <C>                                                                                     <C>
        3.26   Tax Returns, Payments and Elections...............................................9
        3.27   Insurance.........................................................................9
        3.28   Permits...........................................................................9
        3.29   Corporate Documents...............................................................9
        3.30   Manufacturing and Marketing Rights................................................9
        3.31   Preemptive Rights; Rights of First Refusal........................................9
        3.32   Employment Agreement and Invention and Non-Disclosure Agreement...................9

SECTION 4 Representations and Warranties of the Purchasers......................................10

        4.1    Experience.......................................................................10
        4.2    Investment.......................................................................10
        4.3    Rule 144.........................................................................10
        4.4    No Public Market.................................................................10
        4.5    Access to Data...................................................................10
        4.6    Authorization....................................................................11
        4.7    Brokers or Finders...............................................................11

SECTION 5 Conditions to Closing of Purchasers...................................................11

        5.1    Representations and Warranties Correct...........................................11
        5.2    Covenants........................................................................11
        5.3    Compliance Certificate...........................................................11
        5.4    Blue Sky.........................................................................12
        5.5    Articles of Incorporation........................................................12
        5.6    Rights Agreement.................................................................12
        5.7    Opinion of Company's Counsel.....................................................12
        5.8    Employment Agreements............................................................12
        5.9    Consultant Services Agreement....................................................12
        5.10   Secretary's Certificate..........................................................12

SECTION 6 Conditions to Closing of Company......................................................12

        6.1    Representations..................................................................12
        6.2    Blue Sky.........................................................................13
        6.3    Articles of Incorporation........................................................13
        6.4    Covenants........................................................................13
        6.5    Rights Agreement.................................................................13
</TABLE>

                                      -ii-
<PAGE>   4

                               TABLE OF CONTENTS
                                  (CONTINUED)

<TABLE>
<CAPTION>
                                                                                                PAGE
                                                                                                ----
<S>     <C>                                                                                     <C>
SECTION 7 Affirmative Covenants of the Company..................................................13

        7.1    Securities Laws Compliance.......................................................13
        7.2    Employment Agreement and Invention and Non-Disclosure Agreement..................13
        7.3    Related Party Transactions.......................................................13
        7.4    Composition of Company's Board of Directors......................................14
        7.5    Repayment of Bridge Notes........................................................14

SECTION 8 Miscellaneous.........................................................................14

        8.1    Governing Law....................................................................14
        8.2    Survival.........................................................................14
        8.3    Successors and Assigns...........................................................14
        8.4    Entire Agreement, Amendment......................................................15
        8.5    Notices, etc.....................................................................15
        8.6    Delays or Omissions..............................................................15
        8.7    California Corporate Securities Law..............................................16
        8.8    Expenses.........................................................................16
        8.9    Counterparts.....................................................................16
        8.10   Severability.....................................................................16
        8.11   Titles and Subtitles.............................................................16
        8.12   Transfers to Affiliates..........................................................16
</TABLE>

        Exhibit A     Schedule of Purchasers
        Exhibit B     Restated Articles of Incorporation
        Exhibit C     Schedule of Exceptions
        Exhibit D     List of Common Shareholders
        Exhibit E     Registration and Information Rights Agreement
        Exhibit F     Compliance Certificate
        Exhibit G     Opinion of Company Counsel
        Exhibit H-1   Employment Agreement
        Exhibit H-2   Invention and Non-Disclosure Agreement
        Exhibit H-3   Consultant Services Agreement
        Exhibit I     Note Schedule
        Exhibit J     Bridge Note Agreement

                                     -iii-
<PAGE>   5

                         COLLABORATION PROPERTIES, INC.

                   SERIES A PREFERRED STOCK PURCHASE AGREEMENT

        This Series A Preferred Stock Purchase Agreement (the "Agreement") is
made as of December 9, 1999 by and between Collaboration Properties, Inc., a
Nevada corporation (the "Company"), and the purchasers listed in Exhibit A
hereto (collectively, the "Purchasers").

                                    SECTION 1

               Authorization and Sale of Series A Preferred Stock

        1.1 Authorization. The Company will authorize the sale and issuance of
up to 526,315 shares of its Series A Preferred Stock to the Purchasers named on
Exhibit A attached hereto, having the rights, privileges and preferences as set
forth in the Restated Articles of Incorporation (the "Restated Articles") in the
form attached to this Agreement as Exhibit B.

        1.2 Sale of Series A Preferred. Subject to the terms and conditions of
this Agreement, the Purchasers agree to purchase at the Closing (as defined
below) severally and not jointly, and the Company agrees to sell and issue to
the Purchasers, an aggregate of 526,315 shares of the Company's Series A
Preferred Stock (the "Shares" or "Series A Preferred") at a purchase price of
$2.00 per share.

                                    SECTION 2

                             Closing Date; Delivery

        2.1 Closing Date. The closing of the purchase and sale of the Shares
under this Agreement shall be held at the offices of Wilson Sonsini Goodrich &
Rosati, 650 Page Mill Road, Palo Alto, California, at 10 a.m., on December 9,
1999, (the "Closing") or at such other time and place upon which the Company and
the Purchasers shall agree (the date of the Closing is hereinafter referred to
as the "Closing Date").

        2.2 Delivery. At the Closing, the Company will deliver to each Purchaser
a certificate or certificates representing the Shares to be purchased by such
Purchaser at the Closing, against delivery to the Company by such Purchaser of
payment by check or wire transfer of immediately available funds.

<PAGE>   6

                                    SECTION 3

                 Representations and Warranties of the Company.

        Except as set forth on Exhibit C attached to this Agreement, the Company
hereby represents and warrants to the Purchasers as follows:

        3.1 Corporate Organization and Authority. The Company is duly organized,
and is a validly existing corporation in good standing under the laws of the
State of Nevada, authorized to exercise all corporate powers, rights and
privileges, has the corporate power and corporate authority to own and operate
its properties and to carry on its business as now conducted and as proposed to
be conducted as set forth in the Business Plan dated July 1999 delivered by the
Company to the Purchasers (the "Business Plan"), is qualified to do business and
is in good standing in the State of California and is not qualified to do
business as a foreign corporation in any jurisdiction, and such qualification is
not presently required in any jurisdiction where a failure to so qualify would
have a material adverse effect on the Company.

        3.2 Capitalization. Immediately prior to the Closing, the authorized
capital stock of the Company shall consist of:

               (a) Preferred Stock. 600,000 shares of Preferred Stock, all of
which are designated Series A Preferred Stock, and none of which are issued and
outstanding prior to the date hereof. The rights, preferences, privileges and
beneficial restrictions on the Series A Preferred Stock of the Company are set
forth in the Restated Articles, as in effect on the Closing Date. The Company
has reserved an aggregate of 526,315 shares of its Series A Preferred Stock for
issuance hereunder.

               (b) Common Stock. 10,600,000 shares of Common Stock, of which
6,660,000 are duly and validly issued, fully paid, nonassessable, outstanding
and held by the persons and in the amounts set forth on Exhibit D. The Company
has reserved 600,000 shares of Common Stock for issuance upon conversion of the
Series A Preferred Stock. The Company has reserved 3,340,000 shares of Common
Stock for issuance to employees and directors of, and consultants to, the
Company under the 1997 Stock Option Plan, under which there are options
outstanding to purchase 1,950,000 shares of Common Stock, none of which shares
have been exercised, and 1,390,000 shares remain eligible for future issuance.
Except as contemplated by this Agreement there are no other outstanding
warrants, options, conversion privileges, preemptive rights, or other rights or
agreements to purchase or otherwise acquire or issue any equity securities of
the Company. The Company is not a party or subject to any agreement or
understanding, and, to the Company's knowledge, there is no agreement or
understanding between any persons and/or entities, which affects or relates to
the voting or giving of written consents with respect to any security or by a
director of the Company.

                                     - 2 -
<PAGE>   7

        3.3 Subsidiaries. The Company does not presently own, have any
investment in, or control, directly or indirectly, any subsidiaries,
associations or other business entities. The Company is not a participant in any
joint venture or partnership or similar arrangement.

        3.4 Authorization. All corporate action on the part of the Company, its
officers, directors and shareholders necessary for the authorization, execution,
delivery and performance of all obligations under this Agreement and each other
Transaction Agreement (as defined in Section 3.6 below) and for the sale,
issuance and delivery of the Shares, and of the Common Stock issuable upon
conversion of the Shares has been taken, and this Agreement and the Registration
and Information Rights Agreement attached hereto as Exhibit E (the "Rights
Agreement") constitute legally binding valid obligations of the Company
enforceable in accordance with their terms except, to the extent the
indemnification provisions contained in the Agreement may be limited by
applicable federal or state securities laws.

        3.5 Validity of Shares. The Shares, when issued, sold and delivered in
accordance with the terms and for the consideration expressed in this Agreement
shall be duly and validly issued (including, without limitation, issued in
compliance with applicable federal and state securities laws), fully-paid and
nonassessable and free and clear of all liens and encumbrances (other than
those, if any, created or imposed by a Purchaser). The Common Stock issuable
upon conversion of the Shares has been duly and validly reserved, and assuming
such Common Stock is issued to the Purchaser, upon issuance in accordance with
the Restated Articles, shall be duly and validly issued (including, without
limitation, issued in compliance with all applicable federal and state
securities laws), fully-paid and non-assessable.

        3.6 No Conflict with Other Instruments. The execution, delivery and
performance of this Agreement and the Rights Agreement (collectively, the
"Transaction Agreements"), will not result in any violation of, be in conflict
with, or constitute a default under, with or without the passage of time or the
giving of notice: (i) any provision of the Company's Restated Articles or
Bylaws; (ii) any provision of any judgment, decree or order to which the Company
is a party or by which it is bound; (iii) any material contract, obligation or
commitment to which the Company is a party or by which it is bound; (iv) any
agreement or contract providing any other party rights to purchase stock of the
Company or rights to register shares; or (v) any statute, rule or governmental
regulation applicable to the Company.

        3.7 Litigation. There is no action, proceeding or investigation pending
or, to the best of the Company's knowledge, threatened, or any basis therefor
known to the Company, that questions the validity of the Transaction Agreements,
or the right of the Company to enter into the Transaction Agreements, including,
without limitation, any action, suit, proceeding or investigation involving the
prior employment or consultancy of any of the Company's employees or consultants
or their use of any information or techniques alleged to be proprietary to any
former employer of any such employee or consultant. There is no judgment, decree
or order of any court in effect against the Company and the Company is not in
default with respect to any order of any governmental authority to which the
Company is a party or by which it is bound. There is no action, suit, proceeding
or investigation by the Company currently pending or which the Company presently
intends to initiate.

                                     - 3 -
<PAGE>   8

        3.8 Title to Properties, Liens and Encumbrances. The Company has good
and marketable title to all of its properties and assets, both real and
personal, and has good title to all its leasehold interests, in each case
subject to no mortgage, pledge, lien, security interest, conditional sale
agreement, encumbrance or charge.

        3.9    Patents and Other Propriety Rights.

               (a) The Company owns, possesses, has access to or can become
licensed on reasonable terms under all patents, patent applications, trademarks,
trade names, licenses, inventions, computer software, technical information and
copyrights necessary for the operation of its business as now conducted and as
proposed to be conducted (as set forth in the Business Plan) by the Company with
no known infringement of or conflict with the rights of others (nor, to the best
of the Company's knowledge, any basis therefor).

               (b) There are no outstanding options, licenses or agreements of
any kind relating to the matters listed in subsection 3.9(a), nor is the Company
bound by or a party to any options, licenses or agreements of any kind with
respect to the patents, trademarks, service marks, trade names, copyrights,
trade secrets, licenses, information, proprietary rights and processes of any
other person or entity.

               (c) The Company has not received any communications alleging that
the Company has violated or, by conducting its business as proposed, would
violate any of the patents, trademarks, service marks, trade names, copyrights
or trade secrets or any proprietary rights of any other person or entity.

               (d) The Company is not aware that any of its employees is
obligated under any contract (including licenses, covenants or commitments of
any nature) or other agreement, or subject to any judgment, decree or order of
any court or administrative agency, that would interfere with the use of such
employee's best efforts to promote the interests of the Company or that would
conflict with the Company's business as presently conducted.

               (e) The Company is not aware of any resignation or termination of
employment of any key officer of the Company; and the Company, to the best of
its knowledge, does not know of the impending resignation or termination of
employment of any such officer.

               (f) Neither the execution nor delivery of the Transaction
Agreements, nor the carrying on of the Company's business by the employees of
the Company, nor the conduct of the Company's business as presently conducted or
as proposed to be conducted (as set forth in the Business Plan), will, to the
Company's knowledge, conflict with or result in a breach of the terms,
conditions or provisions of, or constitute a default under, any contract,
covenant or instrument under which any of such employees is now obligated.

               (g) The Company does not believe it is or will be necessary to
utilize any inventions of any of its employees (or people it currently intends
to hire) made prior to their employment by the Company and the rights to which
have not been fully assigned to the Company.

                                     - 4 -
<PAGE>   9

               (h) That certain License Agreement, dated December 28, 1997, with
Avistar Systems, L.P. (the "Partnership") has been assigned to Avistar Systems
Corporation, a Nevada corporation ("Avistar") free and clear of all liens,
claims and encumbrances pursuant to the Acquisition Agreement between Avistar
and the Partnership dated as of December 31, 1997, and there are no obligations,
payments, claims or liabilities from Avistar to the Partnership as a result of
such assignment. The Company has not licensed or transferred to any party other
than Avistar any rights, technology or intellectual property that would allow
such other party to use or exploit such rights, technology or intellectual
property in any area, field or market in which Avistar may rightfully be using
or exploiting its rights under the License Agreement. The Company and Avistar
have both fully performed and neither is in default under the License Agreement.

        3.10 Company's Contracts. All of the Company's contracts and agreements
with expected receipts or expenditures in excess of $100,000 or involving a
license or grant of rights to or from the Company involving patents, trademarks,
copyrights or other proprietary information applicable to the business of the
Company, to which the Company is a party as of the date of the Closing are
listed on Exhibit C. All such contracts and agreements are legally binding,
valid, and in full force and effect in all material respects, and there is no
present indication of reduced activity relating to such contract or agreement by
any of the parties to any such contract or agreement.

        3.11 No Defaults, Violations or Conflicts. The Company is not in
violation of any term or provision of its Restated Articles or Bylaws, or any
material term or provision of any indebtedness, mortgage, indenture, contract,
agreement, judgment, statute, rule or regulation, or to the Company's knowledge,
any decree or order.

        3.12 Private Offering. The Company agrees that neither the Company nor
anyone acting on its behalf will offer any of the Shares or any similar
securities for issuance or sale to, or solicit any offering to acquire any of
the same from, anyone so as to make the sale and issuance of the Shares subject
to the registration requirements of Section 5 of the Securities Act of 1933, as
amended (the "Securities Act").

        3.13 Prior Registration Rights. Except as provided in the Rights
Agreement, the Company is under no contractual obligation to register under the
Securities Act any of its presently outstanding securities or any of its
securities that may subsequently be issued.

        3.14 Full Disclosure. The Company has fully provided the Purchasers with
all the information which each Purchaser has requested for deciding whether to
purchase the Shares and all information which the Company believes is reasonably
necessary to enable the Purchaser to make such decision. The representations and
warranties of the Company contained in the Transaction Agreements, certificates
and other documents made or delivered in connection herewith, together with the
Business Plan of the Company previously delivered to the Purchaser, do not
contain any untrue statement of a material fact or omit any material fact
necessary to make the statements contained therein or herein in view of the
circumstances under which they were made not misleading; provided however, that
with respect to the Business Plan, the Company represents only that the Company
reasonably believes there is a reasonable basis for such plan.

                                     - 5 -
<PAGE>   10

        3.15 Related-Party Transactions. No employee, officer or director of the
Company or member of his or her immediate family is indebted to the Company, nor
is the Company indebted (or committed to make loans or extend or guarantee
credit) to any of them. To the best of the Company's knowledge, none of such
persons has any direct or indirect ownership interest in any firm or corporation
with which the Company is affiliated or with which the Company has a business
relationship, or any firm or corporation that competes with the Company, except
that employees, officers, or directors of the Company and members of their
immediate families may own stock in publicly traded companies that may compete
with the Company. No member of the immediate family or any officer or director
of the Company is directly or indirectly interested in any material contract
with the Company.

        3.16 Distributions. There has been no declaration or payment by the
Company of any dividend, nor any distribution by the Company of any assets of
any kind, to any class or series of its capital stock.

        3.17 Employee Compensation Plans. The Company is not a party to or bound
by any currently effective employment contracts, deferred compensation
agreements, bonus plans, incentive plans (other than the 1997 Stock Option
Plan), profit sharing plans, retirement agreements, employee benefit plan
subject to the Employee Retirement Income Security Act of 1974, or other
employee compensation agreements. Subject to applicable law, the employment of
each officer and employee of the Company is terminable at the will of the
Company.

        3.18 Employee Relations. The Company believes its relations with its
employees are satisfactory. None of the Company's employees are represented by
any labor unions nor, to the Company's knowledge, is any union organization
campaign in progress. The Company is not aware that any of its officers or
employees intends to terminate employment.

        3.19 Brokers and Finders. The Company has not retained any investment
banker, broker or finder in connection with the transactions contemplated by
this Agreement. The Company agrees to indemnify and hold harmless each Purchaser
from any liability for any commission or compensation in the nature of a
finders' fee (and the costs and expenses of defending against such liability or
asserted liability) for which the Company or any of its officers, employees or
representatives is responsible.

        3.20 Transactions with Affiliates. Except for (i) the issuance by the
Company of options to purchase shares of the Company's Common Stock, (ii)
regular salary payments and fringe benefits under an individual's compensation
package with the Company and (iii) the License Agreement dated December 28, 1997
with Avistar, pursuant to the terms and conditions of this Agreement, none of
the officers, employees, directors or other affiliates of the Company are a
party to any transactions with the Company. There have been no assumptions or
guarantees by the Company of any obligations of such affiliates.

        3.21 Governmental Consents. No consent, approval, order or authorization
of, or registration, qualification, designation, declaration or filing with, any
federal, state, local or

                                     - 6 -
<PAGE>   11

provincial governmental authority on the part of the Company is required in
connection with the consummation of the transactions contemplated by this
Agreement, except for the filing pursuant to Section 25102(f) of the California
Corporate Securities Law of 1968, as amended, and the rules thereunder, which
filing will be effected within fifteen (15) days after the Closing and any other
filings that may be required pursuant to the securities laws of the applicable
jurisdictions in which the Purchasers reside.

        3.22 Environmental Regulations. Except for failures which will not have
a material adverse effect on the Company, the Company has met, and continues to
meet, all applicable local, state, federal and national environmental
regulations and has disposed of its waste products and effluents and/or has
caused others to dispose of such waste products and effluents, in accordance
with all applicable state, local, federal and national environmental regulations
and in such a manner that no harm has resulted or will result to any of its
respective employees or properties or to any other person or entities or their
properties.

        3.23 Minute Books. The copy of the minute books of the Company provided
to the Purchaser's special counsel contains a complete summary of all meetings
of directors (and any committee of directors) and shareholders and all actions
by written consent thereof since the time of incorporation and reflect all
transactions referred to in such minutes and consents accurately in all material
respects.

        3.24 Financial Statements. The audited balance sheet of the Company
dated December 31, 1998 and related statements of income for the fiscal year
then ended and the unaudited balance sheet dated September 30, 1999 and related
unaudited statements of income for the nine-month period then ended (such
statements are collectively referred to herein as the "Financial Statements"),
are complete and correct in all material respects, present fairly the financial
position and results of operations of the Company at the dates and for the
periods to which they relate, have been prepared in accordance with generally
accepted accounting principles consistently followed throughout the periods
involved, and show all material liabilities, absolute or contingent, of the
Company required to be recorded therein in accordance with generally accepted
accounting principles consistently applied with prior statements as at the date
thereof, except that the Financial Statements have been prepared by the Company
and have not been audited and are subject to normal year-end audit adjustments
and do not contain footnotes normally associated with audited year-end financial
statements. Except as set forth in the Financial Statements, the Company has no
liabilities, contingent or otherwise, other than (i) liabilities incurred in the
ordinary course of business subsequent to September 30, 1999, (ii) obligations
under contracts and commitments incurred in the ordinary course of business and
not required under generally accepted accounting principles to be reflected in
the Financial Statements, which, individually or in the aggregate, are not
material to the financial condition or operating results of the Company and
(iii) obligations under contracts or arrangements described in Section 3.10
hereof or in the Disclosure Schedule.

        3.25 Absence of Certain Changes. Since September 30, 1999 and at all
times up to the Closing, there has not been, nor, so far as reasonably can be
foreseen at this time, is there reasonably likely to be, any event or condition
of any character which has materially adversely affected, or is

                                     - 7 -
<PAGE>   12

likely to affect, the Company's business operations, assets, condition
(financial or otherwise), liabilities, earnings or prospects including but not
limited to:

               (a) an event that would have a material adverse effect on the
business, properties, prospects or financial condition of the Company, or became
reasonably foreseeable, and if it were to occur might adversely affect the
business, properties, prospects or financial conditions of the Company;

               (b) any declaration, setting aside or payment or other
distribution in respect of any of the Company's capital stock, or any direct or
indirect redemption, purchase or other acquisition of any of such stock by the
Company;

               (c) any waiver by the Company of a valuable right or of a
material debt owed to them;

               (d) any material change or amendment to a contract or arrangement
by which the Company or any of their assets or properties is bound or subject;

               (e) any damage, destruction or loss to any asset of the Company
(whether or not covered by insurance) that, individually or in the aggregate,
would have a material adverse effect on the business, properties, prospects or
financial condition of the Company;

               (f) any commitment, transaction or other action by the Company
other than in the ordinary course of business and consistent with past practice;

               (g) any sale or other disposition of any right, title or interest
in or to any assets or properties of the Company or any revenues derived
therefrom other than in the ordinary course of business and consistent with past
practice;

               (h) (x) any approval or action to put into effect any general
increase in any compensation or benefits payable to any class or group of
employees of the Company, any increase in the compensation or benefits payable
or to become payable by the Company to any of their directors, officers or any
of their employees whose total compensation after such increase would exceed
$100,000 per annum (collectively, "Key Employees") or any bonus, service award,
percentage compensation or other benefit paid, granted or accrued to or for the
benefit of any Key Employee or (y) the adoption or amendment in any material
respect of any employee benefit plan or compensation commitment or any severance
agreement or employment contract to which any Key Employee is a party;

               (i) any creation, incurrence or assumption of any indebtedness
for money borrowed by the Company exceeding $100,000;

               (j) any capital expenditures by the Company in excess of
$100,000;

                                     - 8 -
<PAGE>   13

               (k) any material change in any accounting principle or method or
election for federal income tax purposes used by the Company;

               (l) any authorization, approval, agreement or commitment to do
any of the foregoing.

        3.26 Tax Returns, Payments and Elections. The Company has filed all tax
returns and reports as required by law. The Company has not made any elections
pursuant to the Internal Revenue Code of 1986, as amended (the "Code") (other
than elections that relate solely to methods of accounting, depreciation or
amortization) that would have a material effect on the Company, its financial
condition, its business as presently conducted or proposed to be conducted or
any of its properties or material assets.

        3.27 Insurance. The Company has obtained fire and casualty insurance
policies, with extended coverage, sufficient in amount (subject to reasonable
deductibles) to allow the Company to replace any of its properties that might be
damaged or destroyed.

        3.28 Permits. The Company has obtained all franchises, permits, licenses
and any similar authority as necessary for the conduct of its business as now
being conducted by it, the lack of which could materially and adversely affect
(financially or otherwise) the business, properties, assets, liabilities or
prospects of the Company, and believes it can obtain, without undue burden or
expense, any similar authority for the conduct of its business as planned to be
conducted. The Company is not in default in any material respect under any of
such franchises, permits, licenses or other similar authority.

        3.29 Corporate Documents. The Company's Restated Articles and Bylaws are
in the form previously provided to the Purchaser.

        3.30 Manufacturing and Marketing Rights. The Company has not granted
rights to manufacture, produce, assemble, license, market or sell its products
to any other person and is not bound by any agreement that affects the Company's
exclusive right to develop, manufacture, assemble, distribute, market or sell
such products.

        3.31 Preemptive Rights; Rights of First Refusal. No person has any
preemptive right or any right of first refusal in connection with the issuance
of the Shares or any future issuance of securities by the Company.

        3.32 Employment Agreement and Invention and Non-Disclosure Agreement.
Each current and former employee and officer of the Company has executed an
Employment Agreement and Invention and Non-Disclosure Agreement substantially in
the form or forms which have been delivered to special counsel for the
Purchaser.

                                     - 9 -
<PAGE>   14

                                    SECTION 4

                Representations and Warranties of the Purchasers

        Each Purchaser hereby represents and warrants to the Company, severally
and not jointly, with respect to the purchase of the Shares by such Purchaser as
follows:

        4.1 Experience. Such Purchaser has substantial experience in evaluating
and investing in private placement transactions so that such Purchaser is
capable of evaluating the merits and risks of such Purchaser's investment in the
Company. Purchaser, by reason of its business or financial experience or the
business or financial experience of its professional advisors who are
unaffiliated with and who are not compensated by the Company or any affiliate or
selling agent of the Company, directly or indirectly, has the capacity to
protect its own interests in connection with the purchase of the Shares under
this Agreement.

        4.2 Investment. Such Purchaser is acquiring the Shares and the
underlying Common Stock for investment for such Purchaser's own account, not as
a nominee or agent, and not with the view to, or for resale in connection with,
any distribution thereof. Such Purchaser understands that the Shares and the
underlying Common Stock have not been, and will not be, registered under the
Securities Act by reason of a specific exemption therefrom, and that any such
exemption would depend, among other things, upon the bona fide nature of the
investment intent and the accuracy of such Purchaser's representations as
expressed in this Agreement. Such Purchaser has not been formed for the specific
purpose of acquiring the Shares or the underlying Common Stock.

        4.3 Rule 144. Such Purchaser acknowledges that the Shares and the
underlying Common Stock must be held indefinitely unless subsequently registered
under the Securities Act or an exemption from such registration is available.
Such Purchaser is aware of the provisions of Rule 144 promulgated under the
Securities Act which permit limited resale of shares purchased in a private
placement subject to the satisfaction of certain conditions, including, among
other things, the existence of a public market for the shares, the availability
of certain current public information about the Company, the resale occurring
not less than one year after a party has purchased and paid for the security to
be sold, the sale being effected through a "broker's transaction" or in
transactions directly with a "market maker" (as provided by Rule 144(f)) and the
number of shares being sold during any three-month period not exceeding
specified limitations.

        4.4 No Public Market. Such Purchaser understands that no public market
now exists for any of the securities issued by the Company, that the Company has
made no assurances that a public market will ever exist for the Shares or the
underlying Common Stock and that, even if such a public market exists at some
future time, the Company may not then be satisfying the current public
information requirements of Rule 144.

        4.5 Access to Data. Such Purchaser and its representatives have met with
representatives of the Company and thereby have had the opportunity to ask
questions of, and receive answers from,

                                     - 10 -
<PAGE>   15

said representatives concerning the Company and the terms and conditions of this
transaction as well as to obtain any information requested by such Purchaser.
Any questions raised by Purchaser or its representatives concerning the
transaction have been answered to the satisfaction of Purchaser and its
representatives. Such Purchaser's decision to purchase the Shares is based in
part on the answers to such questions as such Purchaser and its representatives
have raised concerning the transaction and on its own evaluation of the risks
and merits of the purchase and the Company's proposed business activities. The
foregoing, however, does not omit or modify the representations and warranties
of the Company in Section 3 of this Agreement or the right of the Purchaser to
rely thereon.

        4.6 Authorization. This Agreement when executed and delivered by the
Purchaser will constitute a valid and legally binding obligation of the
Purchaser, enforceable in accordance with its terms subject to bankruptcy,
insolvency, fraudulent conveyance, moratorium or other laws affecting creditors'
rights generally and to equitable principles of general applicability.

        4.7 Brokers or Finders. The Company has not incurred, and will not
incur, directly or indirectly, as a result of any action taken by the Purchaser
any liability for brokerage or finders' fees or agents' commissions or any
similar charges in connection with this Agreement. The Purchaser agrees to
indemnify and hold harmless the Company from any liability for any commission or
compensation in the nature of a finders' fee ( and the costs and expenses of
defending against such liability or asserted liability) for which the Purchaser
is responsible.

                                    SECTION 5

                       Conditions to Closing of Purchasers

        The Purchaser's obligation to purchase the Shares at the Closing is, at
the option of the Purchasers, subject to the fulfillment or waiver as of the
Closing Date of the following conditions:

        5.1 Representations and Warranties Correct. The representations and
warranties made by the Company in Section 3 of this Agreement shall be true and
correct in all material respects when made, and shall be true and correct in all
material respects on the Closing Date with the same force and effect as if they
had been made on and as of said date.

        5.2 Covenants. All covenants, agreements and conditions contained in
this Agreement to be performed by the Company on or prior to the Closing Date
shall have been performed or complied with in all respects.

        5.3 Compliance Certificate. The Company shall have delivered to each
Purchaser a certificate of the Company in the form attached hereto as Exhibit F,
executed by the President of the Company, dated the Closing Date, and certifying
to the fulfillment of the conditions specified in Sections 5.1 and 5.2 of this
Agreement.

                                     - 11 -
<PAGE>   16

        5.4 Blue Sky. The Company shall have obtained all necessary Blue Sky law
permits and qualifications, or secured exemptions therefrom, required by any
state for the offer and sale of the Shares and the Common Stock issuable upon
conversion of the Shares.

        5.5 Articles of Incorporation. The Restated Articles shall have been
filed with the Secretary of State of the State of Nevada.

        5.6 Rights Agreement. The Company shall have entered into the Rights
Agreement substantially in the form attached hereto as Exhibit E.

        5.7 Opinion of Company's Counsel. At the Closing, the Purchaser shall
have received from Wilson Sonsini Goodrich & Rosati, counsel to the Company, a
favorable opinion addressed to such Purchaser, dated the Closing Date, in
substantially the form attached to this Agreement as Exhibit G.

        5.8 Employment Agreements. Each officer and employee of the Company
shall have entered into an employment agreement in the form of Exhibit H-1
hereto and an invention and non-disclosure agreement in the form of Exhibit H-2
hereto.

        5.9 Consultant Services Agreement. The consultants of the Company shall
each have executed and delivered to the Company a consultant services agreement
substantially in the form of Exhibit H-3 hereto.

        5.10 Secretary's Certificate. The Secretary of the Company shall have
executed and delivered to the Purchaser a certificate dated the Closing Date and
certifying (a) that attached thereto are true and complete copies of the
Restated Articles and the Bylaws of the Company as in effect on the date of such
certificate, (b) that attached thereto are true and correct copies of
resolutions adopted by the Board of Directors of the Company authorizing the
execution, delivery and performance of the Transaction Agreements and that such
resolutions are still in full force and effect and are all the resolutions
adopted in connection with the transactions contemplated by the Transaction
Agreements, and (c) as to the incumbency and specimen signature of each officer
of the Company executing the Transaction Agreements, the stock certificates
representing the Shares and any certificate or instrument furnished pursuant
hereto.

                                    SECTION 6

                        Conditions to Closing of Company

        The Company's obligation to sell and issue the Shares at the Closing is,
at the option of the Company, subject to the fulfillment or waiver of the
following conditions:

        6.1 Representations. The representations made by each Purchaser in
Section 4 of this Agreement shall be true and correct when made, and shall be
true and correct on the Closing Date.

                                     - 12 -
<PAGE>   17

        6.2 Blue Sky. The Company shall have obtained all necessary Blue Sky law
permits and qualifications, or secured exemptions therefrom, required by any
state for the offer and sale of the Shares and the Common Stock issuable upon
conversion of the Shares.

        6.3 Articles of Incorporation. The Restated Articles shall have been
filed with the Secretary of State of the State of Nevada.

        6.4 Covenants. All covenants, agreements and conditions contained in
this Agreement to be performed by the Purchasers on or prior to the Closing Date
shall have been performed or complied with in all material respects.

        6.5 Rights Agreement. The Purchasers shall have entered into the Rights
Agreement substantially in the form attached hereto as Exhibit E.

                                    SECTION 7

                      Affirmative Covenants of the Company

        The Company hereby covenants and agrees as follows:

        7.1 Securities Laws Compliance. The Company shall within fifteen days of
the Closing file a notice of the sale of the Shares to the Purchaser pursuant to
Section 25102(f) of the California Corporations Code.

        7.2 Employment Agreement and Invention and Non-Disclosure Agreement. The
Company shall require all of its future officers and each employee with access
to confidential information regarding the Company's operations or intellectual
property, to execute and deliver an Employment Agreement substantially in the
form attached as Exhibit H-1 hereto and an Invention and Non-Disclosure
Agreement in substantially the form attached as Exhibit H-2 hereto. The Company
shall require all of its future consultants with access to confidential
information regarding the Company's operations, to execute and deliver a
Consulting Agreement in substantially the form attached as Exhibit H-3 hereto.

        7.3 Related Party Transactions. At such time as there are members of the
Company's Board of Directors who are outside directors, all future contracts and
transactions (after taking into account related or similar transactions or
contracts) exceed $100,000 and all material changes contained in renewals or
extensions of such existing contracts and transactions between the Company and
any affiliated entity (including, without limitation, Avistar Systems
Corporation, Collaborative Holdings, Collaboration3, Inc., Visionary Corporate
Technologies, Inc., Vicor, Inc. and Western Data Systems of Nevada, Inc.),
employee, officer, shareholder or director thereof, or any member of his or her
immediate family shall be approved by a majority of the outside directors of the
Company. For purposes of this Section 7.3 and Section 7.4 below, "outside
directors" of the

                                     - 13 -
<PAGE>   18

Company shall be deemed to include only directors who are not officers or
employees, or any member of the immediate family of an officer or employee, of
the Company or any affiliated entity (including, without limitation, any of the
entities described in the preceding sentence). Prior to the appointment of an
outside director (but not after such time), the Company shall obtain the consent
of a majority of the outstanding shares of Series A Preferred Stock prior to
entering into any of the foregoing transactions.

        7.4 Composition of Company's Board of Directors. The Board of Directors
shall consist of four (4) members: Gerald J. Burnett, R. Stephen Heinrichs,
William Campbell, and one representative who shall be chosen by Warburg Dillon
Read, LLC ("WDR"), which representative the Company agrees to cause to be
elected to the Board of Directors so long as WDR holds at least 350,000 shares
of the Series A Preferred Stock.

        7.5 Repayment of Bridge Notes. The Company agrees to consolidate certain
loans referenced on Exhibit I attached hereto and to make such loans payable
subject to the terms of certain Amended and Restated Secured Nonrecourse
Revolving Promissory Notes (each, a "Note"), by and between the Company and the
Heinrichs Revocable Trust, by and between the Company and William L. Campbell,
and by and between the Burnett Revocable Trust, dated as of December 9, 1999,
attached hereto as Exhibit J. The principal and interest on each such Note shall
become fully due and payable upon the earlier of (i) three years from the date
hereof; (ii) the date of consummation of a transaction in which more than 50% of
the Company is not owned by persons who were holders of capital stock or
securities convertible into capital stock of the Company immediately prior to
such transaction or in which the composition of a majority of the Board of
Directors changes; or (iii) 180 days following a firmly underwritten initial
public offering of the Company at an aggregate offering price to the public of
at least $5,000,000 and with an offering price to the public of at least $2.50
per share. The agreement and Notes shall be terminated and canceled promptly
upon the Company's repayment and discharge of such debt.

                                    SECTION 8

                                  Miscellaneous

        8.1 Governing Law. This Agreement shall be governed in all respects by
the laws of the State of California in the United States of America without
giving effect to the conflicts of laws principles thereof.

        8.2 Survival. The representations, warranties, covenants and agreements
made in this Agreement shall survive the closing of the transactions
contemplated hereby, and shall in no way be affected by any investigation of the
subject matter hereof made by or on behalf of the Purchaser or the Company.

        8.3 Successors and Assigns. Except as otherwise provided in this
Agreement, the provisions of this Agreement shall inure to the benefit of, and
be binding upon, the successors,

                                     - 14 -
<PAGE>   19

assigns, heirs, executors and administrators of the parties to this Agreement;
provided, however, that the right of the Purchaser to purchase the Shares shall
not be assignable without the prior written consent of the Company.

        8.4 Entire Agreement, Amendment. This Agreement and the other documents
delivered pursuant to this Agreement at the Closing constitute the full and
entire understanding and agreement between the parties with regard to the
subjects hereof and thereof, and supersede all prior agreements and merge all
prior discussions, negotiations, proposals and offers (written or oral) between
them, and no party shall be liable or bound to any other party in any manner by
any warranties, representations or covenants except as specifically set forth
herein or therein. Except as expressly provided in this Agreement, neither this
Agreement nor any term hereof may be amended, waived, discharged or terminated
other than by a written instrument signed by the party against whom enforcement
of any such amendment, waiver, discharge or termination is sought; provided,
however, that holders of at least a majority of the Shares (or shares of Common
Stock issued upon conversion of the Shares) may, with the written consent of the
Company, waive, modify or amend on behalf of all holders, any provisions hereof
benefiting such holders, so long as the effect thereof will be that all such
holders will be treated equally.

        8.5 Notices, etc. All notices and other communications required or
permitted under this Agreement shall be mailed by registered or certified mail,
postage prepaid, or otherwise delivered by hand or by messenger, addressed (a)
if to a Purchaser, at such Purchaser's address set forth on Exhibit A, or, at
such other address as such Purchaser shall have furnished to the Company in
writing, or (b) if to any other holder of any Shares, at such address as such
holder shall have furnished the Company in writing, or, until any such holder so
furnishes an address to the Company, then to and at the address of the last
holder of such Shares who has so furnished an address to the Company, or (c) if
to the Company, one copy should be sent to its offices and addressed to the
attention of the President, or at such other address as the Company shall have
furnished to the Purchaser.

        Each such notice or other communication shall for all purposes of this
Agreement be treated as effective or having been given when delivered if
delivered personally, or, if sent by mail, at the earlier of its receipt or 72
hours after the same has been deposited in a regularly maintained receptacle for
the deposit of the United States mail, addressed and postage prepaid as
aforesaid.

        8.6 Delays or Omissions. Except as expressly provided in this Agreement,
no delay or omission to exercise any right, power or remedy accruing to any
holder of any Shares, upon any breach or default of the Company under this
Agreement, shall impair any such right, power or remedy of such holder nor shall
it be construed to be a waiver of any such breach or default, or an acquiescence
therein, or of or in any similar breach or default thereafter occurring; nor
shall any waiver of any single breach or default be deemed a waiver of any other
breach or default theretofore or thereafter occurring. Any waiver, permit,
consent or approval of any kind or character on the part of any holder of any
breach or default under this Agreement, or any waiver on the part of any holder
of any provisions or conditions of this Agreement, must be in writing and shall
be effective only to

                                     - 15 -
<PAGE>   20

the extent specifically set forth in such writing. All remedies, either under
this Agreement or by law or otherwise afforded to any holder, shall be
cumulative and not alternative.

        8.7 California Corporate Securities Law. THE SALE OF THE SECURITIES
WHICH ARE THE SUBJECT OF THIS AGREEMENT HAS NOT BEEN QUALIFIED WITH THE
COMMISSIONER OF CORPORATIONS OF THE STATE OF CALIFORNIA AND THE ISSUANCE OF SUCH
SECURITIES OR THE PAYMENT OR RECEIPT OF ANY PART OF THE CONSIDERATION THEREFOR
PRIOR TO SUCH QUALIFICATION IS UNLAWFUL UNLESS THE SALE OF SECURITIES IS EXEMPT
FROM THE QUALIFICATION BY SECTION 25100, 25102 OR 25105 OF THE CALIFORNIA
CORPORATIONS CODE. THE RIGHTS OF ALL PARTIES TO THIS AGREEMENT ARE EXPRESSLY
CONDITIONED UPON SUCH QUALIFICATION BEING OBTAINED, UNLESS THE SALE IS SO
EXEMPT.

        8.8 Expenses. The Company and the Purchaser shall each bear their own
expenses incurred on their behalf with respect to this Agreement and the
transactions contemplated hereby.

        8.9 Counterparts. This Agreement may be executed in any number of
counterparts, each of which shall be enforceable against the parties actually
executing such counterparts, and all of which together shall constitute one
instrument.

        8.10 Severability. In the event that any provision of this Agreement
becomes or is declared by a court of competent jurisdiction to be illegal,
unenforceable or void, this Agreement shall continue in full force and effect
without said provision; provided that no such severability shall be effective if
it materially changes the economic benefit of this Agreement to any party.

        8.11 Titles and Subtitles. The titles and subtitles used in this
Agreement are used for convenience only and are not considered in construing or
interpreting this Agreement.

        8.12 Transfers to Affiliates. Notwithstanding any other provisions of
this Agreement and the Rights Agreement, each Purchaser shall have the right to
transfer the Shares purchased hereunder and its rights under such agreements to
any affiliated entity, corporation, partnership, limited liability company or
investment fund, provided that such affiliate provides in writing to be subject
to the covenants, obligations and conditions set forth in this Agreement and the
Rights Agreement.

                                     - 16 -
<PAGE>   21

            The foregoing agreement is hereby executed as of the date first
above written.

"COMPANY"

COLLABORATION PROPERTIES, INC.
a Nevada corporation

By:
   --------------------------------
     William Campbell
     President & CEO

"PURCHASER"

UBS USA, Inc.

By:
   --------------------------------
     Robert Mills
     Managing Director

By:
   --------------------------------
     By:
     Title:

                            STOCK PURCHASE AGREEMENT
                                 SIGNATURE PAGE

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