<PAGE>   1

                                                                  EXHIBIT 10.1.5


                                  BPO-US, INC.

                            STOCK PURCHASE AGREEMENT
                            ------------------------


         AGREEMENT made this _____ day of ________________ 199__, by and between
BPO-US, Inc., a Delaware corporation, and _______________, Optionee under the
Corporation's 1999 Stock Option/Stock Issuance Plan.

         All capitalized terms in this Agreement shall have the meaning assigned
to them in this Agreement or in the attached Appendix.

         A. EXERCISE OF OPTION

               1. EXERCISE. Optionee hereby purchases _______ shares of Common
Stock (the "Purchased Shares") pursuant to that certain option (the "Option")
granted Optionee on ____________________, 199__ (the "Grant Date") to purchase
up to _______________ shares of Common Stock (the "Option Shares") under the
Plan at the exercise price of $___________ per share (the "Exercise Price").

               2. PAYMENT. Concurrently with the delivery of this Agreement to
the Corporation, Optionee shall pay the Exercise Price for the Purchased Shares
in accordance with the provisions of the Option Agreement and shall deliver
whatever additional documents may be required by the Option Agreement as a
condition for exercise, together with a duly-executed blank Assignment Separate
from Certificate (in the form attached hereto as Exhibit I) with respect to the
Purchased Shares.

               3. STOCKHOLDER RIGHTS. Until such time as the Corporation
exercises the Repurchase Right or the First Refusal Right, Optionee (or any
successor in interest) shall have all the rights of a stockholder (including
voting, dividend and liquidation rights) with respect to the Purchased Shares,
subject, however, to the transfer restrictions of Articles B and C.

         B. SECURITIES LAW COMPLIANCE

               1. RESTRICTED SECURITIES. The Purchased Shares have not been
registered under the 1933 Act and are being issued to Optionee in reliance upon
the exemption from such registration provided by SEC Rule 701 for stock
issuances under compensatory benefit plans such as the Plan. Optionee hereby
confirms that Optionee has been informed that the Purchased Shares are
restricted securities under the 1933 Act and may not be resold or transferred
unless the Purchased Shares are first registered under the Federal securities
laws or unless an exemption from such registration is available. Accordingly,
Optionee hereby acknowledges that Optionee is prepared to hold the Purchased
Shares for an indefinite period and that Optionee is aware that SEC Rule 144
issued under the 1933 Act which exempts certain resales of unrestricted
securities is not presently available to exempt the resale of the Purchased
Shares from the registration requirements of the 1933 Act.

<PAGE>   2

               2. RESTRICTIONS ON DISPOSITION OF PURCHASED SHARES. Optionee
shall make no disposition of the Purchased Shares (other than a Permitted
Transfer) unless and until there is compliance with all of the following
requirements:

                  (i) Optionee shall have provided the Corporation with a
         written summary of the terms and conditions of the proposed
         disposition.

                  (ii) Optionee shall have complied with all requirements of
         this Agreement applicable to the disposition of the Purchased Shares.

                  (iii) Optionee shall have provided the Corporation with
         written assurances, in form and substance satisfactory to the
         Corporation, that (a) the proposed disposition does not require
         registration of the Purchased Shares under the 1933 Act or (b) all
         appropriate action necessary for compliance with the registration
         requirements of the 1933 Act or any exemption from registration
         available under the 1933 Act (including Rule 144) has been taken.

                  The Corporation shall not be required (i) to transfer on its
books any Purchased Shares which have been sold or transferred in violation of
the provisions of this Agreement or (ii) to treat as the owner of the Purchased
Shares, or otherwise to accord voting, dividend or liquidation rights to, any
transferee to whom the Purchased Shares have been transferred in contravention
of this Agreement.

         3. RESTRICTIVE LEGENDS. The stock certificates for the Purchased Shares
shall be endorsed with one or more of the following restrictive legends:

                  "The shares represented by this certificate have not been
         registered under the Securities Act of 1933. The shares may not be sold
         or offered for sale in the absence of (a) an effective registration
         statement for the shares under such Act, (b) a "no action" letter of
         the Securities and Exchange Commission with respect to such sale or
         offer or (c) satisfactory assurances to the Corporation that
         registration under such Act is not required with respect to such sale
         or offer."

                  "The shares represented by this certificate are subject to
         certain repurchase rights and rights of first refusal granted to the
         Corporation and accordingly may not be sold, assigned, transferred,
         encumbered, or in any manner disposed of except in conformity with the
         terms of a written agreement dated ____________, 199___ between the
         Corporation and the registered holder of the shares (or the predecessor
         in interest to the shares). A copy of such agreement is maintained at
         the Corporation's principal corporate offices."


                                       2.
<PAGE>   3

         C. TRANSFER RESTRICTIONS

               1. RESTRICTION ON TRANSFER. Except for any Permitted Transfer,
Optionee shall not transfer, assign, encumber or otherwise dispose of any of the
Purchased Shares which are subject to the Repurchase Right. In addition,
Purchased Shares which are released from the Repurchase Right shall not be
transferred, assigned, encumbered or otherwise disposed of in contravention of
the First Refusal Right or the Market Stand-Off.

               2. TRANSFEREE OBLIGATIONS. Each person (other than the
Corporation) to whom the Purchased Shares are transferred by means of a
Permitted Transfer must, as a condition precedent to the validity of such
transfer, acknowledge in writing to the Corporation that such person is bound by
the provisions of this Agreement and that the transferred shares are subject to
(i) the Repurchase Right, (ii) the First Refusal Right and (iii) the Market
Stand-Off, to the same extent such shares would be so subject if retained by
Optionee.

               3. MARKET STAND-OFF.

                    (a) In connection with any underwritten public offering by
the Corporation of its equity securities pursuant to an effective registration
statement filed under the 1933 Act, including the Corporation's initial public
offering, Owner shall not sell, make any short sale of, loan, hypothecate,
pledge, grant any option for the purchase of, or otherwise dispose or transfer
for value or otherwise agree to engage in any of the foregoing transactions with
respect to, any Purchased Shares without the prior written consent of the
Corporation or its underwriters. Such restriction (the "Market Stand-Off") shall
be in effect for such period of time from and after the effective date of the
final prospectus for the offering as may be requested by the Corporation or such
underwriters. In no event, however, shall such period exceed one hundred eighty
(180) days and the Market Stand-Off shall in all events terminate two (2) years
after the effective date of the Corporation's initial public offering.

                    (b) Ownershall be subject to the Market Stand-Off provided
and only if the officers and directors of the Corporation are also subject to
similar restrictions.

                    (c) Any new, substituted or additional securities which are
by reason of any Recapitalization or Reorganization distributed with respect to
the Purchased Shares shall be immediately subject to the Market Stand-Off, to
the same extent the Purchased Shares are at such time covered by such
provisions.

                    (d) In order to enforce the Market Stand-Off, the
Corporation may impose stop-transfer instructions with respect to the Purchased
Shares until the end of the applicable stand-off period.


                                       3.
<PAGE>   4

         D. REPURCHASE RIGHT

               1. GRANT. The Corporation is hereby granted the right (the
"Repurchase Right"), exercisable at any time during the sixty (60)-day period
following the date Optionee ceases for any reason to remain in Service or (if
later) during the sixty (60)-day period following the execution date of this
Agreement, to repurchase at the Exercise Price any or all of the Purchased
Shares in which Optionee is not, at the time of his or her cessation of Service,
vested in accordance with the Vesting Schedule applicable to those shares or the
special vesting acceleration provisions of Paragraph D.6 of this Agreement (such
shares to be hereinafter referred to as the "Unvested Shares").

               2. EXERCISE OF THE REPURCHASE RIGHT. The Repurchase Right shall
be exercisable by written notice delivered to each Owner of the Unvested Shares
prior to the expiration of the sixty (60)-day exercise period. The notice shall
indicate the number of Unvested Shares to be repurchased and the date on which
the repurchase is to be effected, such date to be not more than thirty (30) days
after the date of such notice. The certificates representing the Unvested Shares
to be repurchased shall be delivered to the Corporation on or before the close
of business on the date specified for the repurchase. Concurrently with the
receipt of such stock certificates, the Corporation shall pay to Owner, in cash
or cash equivalents (including the cancellation of any purchase-money
indebtedness), an amount equal to the Exercise Price previously paid for the
Unvested Shares which are to be repurchased from Owner.

               3. TERMINATION OF THE REPURCHASE RIGHT. The Repurchase Right
shall terminate with respect to any Unvested Shares for which it is not timely
exercised under Paragraph D.2. In addition, the Repurchase Right shall terminate
and cease to be exercisable with respect to any and all Purchased Shares in
which Optionee vests in accordance with the Vesting Schedule. All Purchased
Shares as to which the Repurchase Right lapses shall, however, remain subject to
(i) the First Refusal Right and (ii) the Market Stand-Off.

               4. AGGREGATE VESTING LIMITATION. If the Option is exercised in
more than one increment so that Optionee is a party to one or more other Stock
Purchase Agreements (the "Prior Purchase Agreements") which are executed prior
to the date of this Agreement, then the total number of Purchased Shares as to
which Optionee shall be deemed to have a fully-vested interest under this
Agreement and all Prior Purchase Agreements shall not exceed in the aggregate
the number of Purchased Shares in which Optionee would otherwise at the time be
vested, in accordance with the Vesting Schedule, had all the Purchased Shares
(including those acquired under the Prior Purchase Agreements) been acquired
exclusively under this Agreement.

               5. RECAPITALIZATION. Any new, substituted or additional
securities or other property (including cash paid other than as a regular cash
dividend) which is by reason of any Recapitalization distributed with respect to
the Purchased Shares shall be immediately subject to the Repurchase Right and
any escrow requirements hereunder, but only to the extent the Purchased Shares
are at the time covered by such right or escrow requirements. Appropriate
adjustments to reflect such distribution shall be made to the number and/or
class of Purchased Shares subject to this Agreement and to the price per share
to be paid upon the exercise of the Repurchase Right in order to reflect the
effect of any such Recapitalization upon the


                                       4.
<PAGE>   5

Corporation's capital structure; provided, however, that the aggregate purchase
price shall remain the same.

         6. CORPORATE TRANSACTION.

               (a) The Repurchase Right shall automatically terminate in its
entirety, and all the Purchased Shares shall vest in full, immediately prior to
the consummation of any Corporate Transaction, except to the extent the
Repurchase Right is to be assigned to the successor entity in such Corporate
Transaction.

               (b) To the extent the Repurchase Right remains in effect
following a Corporate Transaction, such right shall apply to any new securities
or other property (including any cash payments) received in exchange for the
Purchased Shares in consummation of the Corporate Transaction, but only to the
extent the Purchased Shares are at the time covered by such right. Appropriate
adjustments shall be made to the price per share payable upon exercise of the
Repurchase Right to reflect the effect of the Corporate Transaction upon the
Corporation's capital structure; provided, however, that the aggregate purchase
price shall remain the same. The new securities or other property (including any
cash payments) issued or distributed with respect to the Purchased Shares in
consummation of the Corporate Transaction shall be immediately deposited in
escrow with the Corporation (or the successor entity) and shall not be released
from escrow until Optionee vests in such securities or other property in
accordance with the same Vesting Schedule in effect for the Purchased Shares.

               (c) The Repurchase Right may also terminate on an accelerated
basis, and the Purchased Shares shall immediately vest in full, in accordance
with the terms and conditions of any special addendum attached to this
Agreement.

         E. RIGHT OF FIRST REFUSAL

               1. GRANT. The Corporation is hereby granted the right of first
refusal (the "First Refusal Right"), exercisable in connection with any proposed
transfer of the Purchased Shares in which Optionee has vested in accordance with
the provisions of Article D. For purposes of this Article E, the term "transfer"
shall include any sale, assignment, pledge, encumbrance or other disposition of
the Purchased Shares intended to be made by Owner, but shall not include any
Permitted Transfer.

               2. NOTICE OF INTENDED DISPOSITION. In the event any Owner of
Purchased Shares in which Optionee has vested desires to accept a bona fide
third-party offer for the transfer of any or all of such shares (the Purchased
Shares subject to such offer to be hereinafter referred to as the "Target
Shares"), Owner shall promptly (i) deliver to the Corporation written notice
(the "Disposition Notice") of the terms of the offer, including the purchase
price and the identity of the third-party offeror, and (ii) provide satisfactory
proof that the disposition of the Target Shares to such third-party offeror
would not be in contravention of the provisions set forth in Articles B and C.


                                       5.
<PAGE>   6

               3. EXERCISE OF THE FIRST REFUSAL RIGHT. The Corporation shall,
for a period of twenty-five (25) days following receipt of the Disposition
Notice, have the right to repurchase any or all of the Target Shares subject to
the Disposition Notice upon the same terms as those specified therein or upon
such other terms (not materially different from those specified in the
Disposition Notice) to which Owner consents. Such right shall be exercisable by
delivery of written notice (the "Exercise Notice") to Owner prior to the
expiration of the twenty-five (25)-day exercise period. If such right is
exercised with respect to all the Target Shares, then the Corporation shall
effect the repurchase of such shares, including payment of the purchase price,
not more than five (5) business days after delivery of the Exercise Notice; and
at such time the certificates representing the Target Shares shall be delivered
to the Corporation.

               Should the purchase price specified in the Disposition Notice be
payable in property other than cash or evidences of indebtedness, the
Corporation shall have the right to pay the purchase price in the form of cash
equal in amount to the value of such property. If Owner and the Corporation
cannot agree on such cash value within ten (10) days after the Corporation's
receipt of the Disposition Notice, the valuation shall be made by an appraiser
of recognized standing selected by Owner and the Corporation or, if they cannot
agree on an appraiser within twenty (20) days after the Corporation's receipt of
the Disposition Notice, each shall select an appraiser of recognized standing
and the two (2) appraisers shall designate a third appraiser of recognized
standing, whose appraisal shall be determinative of such value. The cost of such
appraisal shall be shared equally by Owner and the Corporation. The closing
shall then be held on the later of (i) the fifth (5th) business day following
delivery of the Exercise Notice or (ii) the fifth (5th) business day after such
valuation shall have been made.

               4. NON-EXERCISE OF THE FIRST REFUSAL RIGHT. In the event the
Exercise Notice is not given to Owner prior to the expiration of the twenty-five
(25)-day exercise period, Owner shall have a period of thirty (30) days
thereafter in which to sell or otherwise dispose of the Target Shares to the
third-party offeror identified in the Disposition Notice upon terms (including
the purchase price) no more favorable to such third-party offeror than those
specified in the Disposition Notice; provided, however, that any such sale or
disposition must not be effected in contravention of the provisions of Articles
B and C. The third-party offeror shall acquire the Target Shares free and clear
of the First Refusal Right, but the acquired shares shall remain subject to the
provisions of Article B and Paragraph C.3. In the event Owner does not effect
such sale or disposition of the Target Shares within the specified thirty
(30)-day period, the First Refusal Right shall continue to be applicable to any
subsequent disposition of the Target Shares by Owner until such right lapses.

               5. PARTIAL EXERCISE OF THE FIRST REFUSAL RIGHT. In the event the
Corporation makes a timely exercise of the First Refusal Right with respect to a
portion, but not all, of the Target Shares specified in the Disposition Notice,
Owner shall have the option, exercisable by written notice to the Corporation
delivered within five (5) business days after Owner's receipt of the Exercise
Notice, to effect the sale of the Target Shares pursuant to either of the
following alternatives:


                                       6.
<PAGE>   7

                  (i) sale or other disposition of all the Target Shares to the
         third-party offeror identified in the Disposition Notice, but in full
         compliance with the requirements of Paragraph E.4, as if the
         Corporation did not exercise the First Refusal Right; or

                  (ii) sale to the Corporation of the portion of the Target
         Shares which the Corporation has elected to purchase, such sale to be
         effected in substantial conformity with the provisions of Paragraph
         E.3. The First Refusal Right shall continue to be applicable to any
         subsequent disposition of the remaining Target Shares until such right
         lapses.

               Owner's failure to deliver timely notification to the Corporation
shall be deemed to be an election by Owner to sell the Target Shares pursuant to
alternative (i) above.

               6. RECAPITALIZATION/REORGANIZATION.

                    (a) Any new, substituted or additional securities or other
property which is by reason of any Recapitalization distributed with respect to
the Purchased Shares shall be immediately subject to the First Refusal Right,
but only to the extent the Purchased Shares are at the time covered by such
right.

                    (b) In the event of a Reorganization, the First Refusal
Right shall remain in full force and effect and shall apply to the new capital
stock or other property received in exchange for the Purchased Shares in
consummation of the Reorganization, but only to the extent the Purchased Shares
are at the time covered by such right.

               7. LAPSE. The First Refusal Right shall lapse upon the earliest
to occur of (i) the first date on which shares of the Common Stock are held of
record by more than five hundred (500) persons, (ii) a determination made by the
Board that a public market exists for the outstanding shares of Common Stock or
(iii) a firm commitment underwritten public offering, pursuant to an effective
registration statement under the 1933 Act, covering the offer and sale of the
Common Stock in the aggregate amount of at least ten million dollars
($10,000,000). However, the Market Stand-Off shall continue to remain in full
force and effect following the lapse of the First Refusal Right.

         F. SPECIAL TAX ELECTION

               The acquisition of the Purchased Shares may result in adverse tax
consequences which may be avoided or mitigated by filing an election under Code
Section 83(b). Such election must be filed within thirty (30) days after the
date of this Agreement. A description of the tax consequences applicable to the
acquisition of the Purchased Shares and the form for making the Code Section
83(b) election are set forth in Exhibit II. OPTIONEE SHOULD CONSULT WITH HIS OR
HER TAX ADVISOR TO DETERMINE THE TAX CONSEQUENCES OF ACQUIRING THE PURCHASED
SHARES AND THE ADVANTAGES AND DISADVANTAGES OF FILING THE CODE SECTION 83(b)
ELECTION. OPTIONEE ACKNOWLEDGES THAT IT IS OPTIONEE'S SOLE


                                       7.
<PAGE>   8

RESPONSIBILITY, AND NOT THE CORPORATION'S, TO FILE A TIMELY ELECTION UNDER CODE
SECTION 83(b), EVEN IF OPTIONEE REQUESTS THE CORPORATION OR ITS REPRESENTATIVES
TO MAKE THIS FILING ON HIS OR HER BEHALF.

         G. GENERAL PROVISIONS

               1. ASSIGNMENT. The Corporation may assign the Repurchase Right
and/or the First Refusal Right to any person or entity selected by the Board,
including (without limitation) one or more stockholders of the Corporation.

               2. NO EMPLOYMENT OR SERVICE CONTRACT. Nothing in this Agreement
or in the Plan shall confer upon Optionee any right to continue in Service for
any period of specific duration or interfere with or otherwise restrict in any
way the rights of the Corporation (or any Parent or Subsidiary employing or
retaining Optionee) or of Optionee, which rights are hereby expressly reserved
by each, to terminate Optionee's Service at any time for any reason, with or
without cause.

               3. NOTICES. Any notice required to be given under this Agreement
shall be in writing and shall be deemed effective upon personal delivery or upon
deposit in the U.S. mail, registered or certified, postage prepaid and properly
addressed to the party entitled to such notice at the address indicated below
such party's signature line on this Agreement or at such other address as such
party may designate by ten (10) days advance written notice under this paragraph
to all other parties to this Agreement.

               4. NO WAIVER. The failure of the Corporation in any instance to
exercise the Repurchase Right or the First Refusal Right shall not constitute a
waiver of any other repurchase rights and/or rights of first refusal that may
subsequently arise under the provisions of this Agreement or any other agreement
between the Corporation and Optionee. No waiver of any breach or condition of
this Agreement shall be deemed to be a waiver of any other or subsequent breach
or condition, whether of like or different nature.

               5. CANCELLATION OF SHARES. If the Corporation shall make
available, at the time and place and in the amount and form provided in this
Agreement, the consideration for the Purchased Shares to be repurchased in
accordance with the provisions of this Agreement, then from and after such time,
the person from whom such shares are to be repurchased shall no longer have any
rights as a holder of such shares (other than the right to receive payment of
such consideration in accordance with this Agreement). Such shares shall be
deemed purchased in accordance with the applicable provisions hereof, and the
Corporation shall be deemed the owner and holder of such shares, whether or not
the certificates therefor have been delivered as required by this Agreement.


                                       8.
<PAGE>   9

         H. MISCELLANEOUS PROVISIONS

               1. OPTIONEE UNDERTAKING. Optionee hereby agrees to take whatever
additional action and execute whatever additional documents the Corporation may
deem necessary or advisable in order to carry out or effect one or more of the
obligations or restrictions imposed on either Optionee or the Purchased Shares
pursuant to the provisions of this Agreement.

               2. AGREEMENT IS ENTIRE CONTRACT. This Agreement constitutes the
entire contract between the parties hereto with regard to the subject matter
hereof. This Agreement is made pursuant to the provisions of the Plan and shall
in all respects be construed in conformity with the terms of the Plan.

               3. GOVERNING LAW. This Agreement shall be governed by, and
construed in accordance with, the laws of the State of California without resort
to that State's conflict-of-laws rules.

               4. COUNTERPARTS. This Agreement may be executed in counterparts,
each of which shall be deemed to be an original, but all of which together shall
constitute one and the same instrument.


                                       9.
<PAGE>   10

               5. SUCCESSORS AND ASSIGNS. The provisions of this Agreement shall
inure to the benefit of, and be binding upon, the Corporation and its successors
and assigns and upon Optionee, Optionee's permitted assigns and the legal
representatives, heirs and legatees of Optionee's estate, whether or not any
such person shall have become a party to this Agreement and have agreed in
writing to join herein and be bound by the terms hereof.

               IN WITNESS WHEREOF, the parties have executed this Agreement on
the day and year first indicated above.



                                  BPO-US, INC.

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

                                             -----------------------------------



                                             -----------------------------------
                                             OPTIONEE

                                  Address:
                                             -----------------------------------

                                             -----------------------------------


                                      10.
<PAGE>   11

                             SPOUSAL ACKNOWLEDGMENT


         The undersigned spouse of Optionee has read and hereby approves the
foregoing Stock Purchase Agreement. In consideration of the Corporation's
granting Optionee the right to acquire the Purchased Shares in accordance with
the terms of such Agreement, the undersigned hereby agrees to be irrevocably
bound by all the terms of such Agreement, including (without limitation) the
right of the Corporation (or its assigns) to purchase any Purchased Shares in
which Optionee is not vested at time of his or her cessation of Service.



                                              ----------------------------------
                                              OPTIONEE'S SPOUSE

                                  Address:
                                              ----------------------------------

                                              ----------------------------------

<PAGE>   12

                                    EXHIBIT I

                      ASSIGNMENT SEPARATE FROM CERTIFICATE

         FOR VALUE RECEIVED ____________ hereby sell(s), assign(s) and
transfer(s) unto BPO-US, Inc. (the "Corporation"), _______________ (_________)
shares of the Common Stock of the Corporation standing in his or her name on the
books of the Corporation represented by Certificate No. ________________
herewith and do(es) hereby irrevocably constitute and appoint
_____________________ Attorney to transfer the said stock on the books of the
Corporation with full power of substitution in the premises.

Dated: ____________________






                                    Signature
                                              ----------------------------------




INSTRUCTION: Please do not fill in any blanks other than the signature line.
Please sign exactly as you would like your name to appear on the issued stock
certificate. The purpose of this assignment is to enable the Corporation to
exercise the Repurchase Right without requiring additional signatures on the
part of Optionee.

<PAGE>   13

                                   EXHIBIT II

                       FEDERAL INCOME TAX CONSEQUENCES AND
                           SECTION 83(b) TAX ELECTION

         I. FEDERAL INCOME TAX CONSEQUENCES AND SECTION 83(b) ELECTION FOR
EXERCISE OF NON-STATUTORY OPTION. If the Purchased Shares are acquired pursuant
to the exercise of a Non-Statutory Option, as specified in the Grant Notice,
then under Code Section 83, the excess of the Fair Market Value of the Purchased
Shares on the date any forfeiture restrictions applicable to such shares lapse
over the Exercise Price paid for such shares will be reportable as ordinary
income on the lapse date. For this purpose, the term "forfeiture restrictions"
includes the right of the Corporation to repurchase the Purchased Shares
pursuant to the Repurchase Right. However, Optionee may elect under Code Section
83(b) to be taxed at the time the Purchased Shares are acquired, rather than
when and as such Purchased Shares cease to be subject to such forfeiture
restrictions. Such election must be filed with the Internal Revenue Service
within thirty (30) days after the date of the Agreement. Even if the Fair Market
Value of the Purchased Shares on the date of the Agreement equals the Exercise
Price paid (and thus no tax is payable), the election must be made to avoid
adverse tax consequences in the future. The form for making this election is
attached as part of this exhibit. FAILURE TO MAKE THIS FILING WITHIN THE
APPLICABLE THIRTY (30)-DAY PERIOD WILL RESULT IN THE RECOGNITION OF ORDINARY
INCOME BY OPTIONEE AS THE FORFEITURE RESTRICTIONS LAPSE.

         II. FEDERAL INCOME TAX CONSEQUENCES AND CONDITIONAL SECTION 83(b)
ELECTION FOR EXERCISE OF INCENTIVE Option. If the Purchased Shares are acquired
pursuant to the exercise of an Incentive Option, as specified in the Grant
Notice, then the following tax principles shall be applicable to the Purchased
Shares:

                  (i) For regular tax purposes, no taxable income will be
         recognized at the time the Option is exercised.

                  (ii) The excess of (a) the Fair Market Value of the Purchased
         Shares on the date the Option is exercised or (if later) on the date
         any forfeiture restrictions applicable to the Purchased Shares lapse
         over (b) the Exercise Price paid for the Purchased Shares will be
         includible in Optionee's taxable income for alternative minimum tax
         purposes.

                  (iii) If Optionee makes a disqualifying disposition of the
         Purchased Shares, then Optionee will recognize ordinary income in the
         year of such disposition equal in amount to the excess of (a) the Fair
         Market Value of the Purchased Shares on the date the Option is
         exercised or (if later) on the date any forfeiture restrictions
         applicable to the Purchased Shares lapse over (b) the Exercise Price
         paid for the Purchased Shares. Any additional gain recognized upon the
         disqualifying disposition will be either short-term or long-term
         capital gain depending upon the period for which the Purchased Shares
         are held prior to the disposition.


                                     II-1.
<PAGE>   14

                  (iv) For purposes of the foregoing, the term "forfeiture
         restrictions" will include the right of the Corporation to repurchase
         the Purchased Shares pursuant to the Repurchase Right. The term
         "disqualifying disposition" means any sale or other disposition(1) of
         the Purchased Shares within two (2) years after the Grant Date or
         within one (1) year after the exercise date of the Option.

                  (v) In the absence of final Treasury Regulations relating to
         Incentive Options, it is not certain whether Optionee may, in
         connection with the exercise of the Option for any Purchased Shares at
         the time subject to forfeiture restrictions, file a protective election
         under Code Section 83(b) which would limit (a) Optionee's alternative
         minimum taxable income upon exercise and (b) Optionee's ordinary income
         upon a disqualifying disposition to the excess of the Fair Market Value
         of the Purchased Shares on the date the Option is exercised over the
         Exercise Price paid for the Purchased Shares. Accordingly, such
         election if properly filed will only be allowed to the extent the final
         Treasury Regulations permit such a protective election. Page 2 of the
         attached form for making the election should be filed with any election
         made in connection with the exercise of an Incentive Option.



--------
(1) Generally, a disposition of shares purchased under an Incentive Option
includes any transfer of legal title, including a transfer by sale, exchange or
gift, but does not include a transfer to the Optionee's spouse, a transfer into
joint ownership with right of survivorship if Optionee remains one of the joint
owners, a pledge, a transfer by bequest or inheritance or certain tax free
exchanges permitted under the Code.


                                     II-2.
<PAGE>   15

                             SECTION 83(b) ELECTION


         This statement is being made under Section 83(b) of the Internal
Revenue Code, pursuant to Treas. Reg. Section 1.83-2.

(1)      The taxpayer who performed the services is:

         Name:
         Address:
         Taxpayer Ident. No.:

(2)      The property with respect to which the election is being made is
         _____________ shares of the common stock of BPO-US, Inc.

(3)      The property was issued on ______________, 199__

(4)      The taxable year in which the election is being made is the calendar
         year 199__.

(5)      The property is subject to a repurchase right pursuant to which the
         issuer has the right to acquire the property at the original purchase
         price if for any reason taxpayer's service with the issuer terminates.
         The issuer's repurchase right lapses in a series of annual and monthly
         installments over a four (4)-year period ending on ___________, 200__.

(6)      The fair market value at the time of transfer (determined without
         regard to any restriction other than a restriction which by its terms
         will never lapse) is $__________per share.

(7)      The amount paid for such property is $___________ per share.

(8)      A copy of this statement was furnished to BPO-US, Inc. for whom
         taxpayer rendered the services underlying the transfer of property.

(9)      This statement is executed on _________________, 199__.


----------------------------------          ------------------------------------
Spouse (if any)                             Taxpayer

This election must be filed with the Internal Revenue Service Center with which
taxpayer files his or her Federal income tax returns and must be made within
thirty (30) days after the execution date of the Stock Purchase Agreement. This
filing should be made by registered or certified mail, return receipt requested.
Optionee must retain two (2) copies of the completed form for filing with his or
her Federal and state tax returns for the current tax year and an additional
copy for his or her records.

<PAGE>   16

         The property described in the above Section 83(b) election is comprised
of shares of common stock acquired pursuant to the exercise of an incentive
stock option under Section 422 of the Internal Revenue Code (the "Code").
Accordingly, it is the intent of the Taxpayer to utilize this election to
achieve the following tax results:

         1. The purpose of this election is to have the alternative minimum
taxable income attributable to the purchased shares measured by the amount by
which the fair market value of such shares at the time of their transfer to the
Taxpayer exceeds the purchase price paid for the shares. In the absence of this
election, such alternative minimum taxable income would be measured by the
spread between the fair market value of the purchased shares and the purchase
price which exists on the various lapse dates in effect for the forfeiture
restrictions applicable to such shares

         2. Section 421(a)(1) of the Code expressly excludes from income any
excess of the fair market value of the purchased shares over the amount paid for
such shares. Accordingly, this election is also intended to be effective in the
event there is a "disqualifying disposition" of the shares, within the meaning
of Section 421(b) of the Code, which would otherwise render the provisions of
Section 83(a) of the Code applicable at that time. Consequently, the Taxpayer
hereby elects to have the amount of disqualifying disposition income measured by
the excess of the fair market value of the purchased shares on the date of
transfer to the Taxpayer over the amount paid for such shares. Since Section
421(a) presently applies to the shares which are the subject of this Section
83(b) election, no taxable income is actually recognized for regular tax
purposes at this time, and no income taxes are payable, by the Taxpayer as a
result of this election.. The foregoing election is to be effective to the full
extent permitted under the Code.


THIS PAGE 2 IS TO BE ATTACHED TO ANY SECTION 83(b) ELECTION FILED IN CONNECTION
WITH THE EXERCISE OF AN INCENTIVE STOCK OPTION UNDER THE FEDERAL TAX LAWS.


                                       2.
<PAGE>   17

                                    APPENDIX
                                    --------


        The following definitions shall be in effect under the Agreement:

         A. AGREEMENT shall mean this Stock Purchase Agreement.

         B. BOARD shall mean the Corporation's Board of Directors.

         C. CODE shall mean the Internal Revenue Code of 1986, as amended.

         D. COMMON STOCK shall mean the Corporation's common stock.

         E. CORPORATE TRANSACTION shall mean either of the following
stockholder-approved transactions:

                  (i) a merger or consolidation in which securities possessing
         more than fifty percent (50%) of the total combined voting power of the
         Corporation's outstanding securities are transferred to a person or
         persons different from the persons holding those securities immediately
         prior to such transaction, or

                  (ii) the sale, transfer or other disposition of all or
         substantially all of the Corporation's assets in complete liquidation
         or dissolution of the Corporation.

         F. CORPORATION shall mean BPO-US, Inc., a Delaware corporation, and any
successor corporation to all or substantially all of the assets or voting stock
of BPO-US, Inc. which shall by appropriate action adopt the Plan.

         G. DISPOSITION NOTICE shall have the meaning assigned to such term in
Paragraph E.2.

         H. EXERCISE NOTICE shall have the meaning assigned to such term in
Paragraph E.3.

         I. EXERCISE PRICE shall have the meaning assigned to such term in
Paragraph A.1.

         J. FAIR MARKET VALUE of a share of Common Stock on any relevant date,
prior to the initial public offering of the Common Stock, shall be determined by
the Plan Administrator after taking into account such factors as it shall deem
appropriate.

         K. FIRST REFUSAL RIGHT shall mean the right granted to the Corporation
in accordance with Article E.

         L. GRANT DATE shall have the meaning assigned to such term in Paragraph
A.1.


                                      A-1.
<PAGE>   18

         M. GRANT NOTICE shall mean the Notice of Grant of Stock Option pursuant
to which Optionee has been informed of the basic terms of the Option.

         N. INCENTIVE OPTION shall mean an option which satisfies the
requirements of Code Section 422.

         O. MARKET STAND-OFF shall mean the market stand-off restriction
specified in Paragraph C.3.

         P. 1933 ACT shall mean the Securities Act of 1933, as amended.

         Q. 1934 ACT shall mean the Securities Exchange Act of 1934, as amended.

         R. NON-STATUTORY OPTION shall mean an option not intended to satisfy
the requirements of Code Section 422.

         S. OPTION shall have the meaning assigned to such term in Paragraph
A.1.

         T. OPTION AGREEMENT shall mean all agreements and other documents
evidencing the Option.

         U. OPTIONEE shall mean the person to whom the Option is granted under
the Plan.

         V. OWNER shall mean Optionee and all subsequent holders of the
Purchased Shares who derive their chain of ownership through a Permitted
Transfer from Optionee.

         W. PARENT shall mean any corporation (other than the Corporation) in an
unbroken chain of corporations ending with the Corporation, provided each
corporation in the unbroken chain (other than the Corporation) owns, at the time
of the determination, stock possessing fifty percent (50%) or more of the total
combined voting power of all classes of stock in one of the other corporations
in such chain.

         X. PERMITTED TRANSFER shall mean (i) a gratuitous transfer of the
Purchased Shares, provided and only if Optionee obtains the Corporation's prior
written consent to such transfer, (ii) a transfer of title to the Purchased
Shares effected pursuant to Optionee's will or the laws of intestate succession
following Optionee's death or (iii) a transfer to the Corporation in pledge as
security for any purchase-money indebtedness incurred by Optionee in connection
with the acquisition of the Purchased Shares.

         Y. PLAN shall mean the Corporation's 1999 Stock Option/Stock Issuance
Plan.

         Z. PLAN ADMINISTRATOR shall mean either the Board or a committee of the
Board acting in its capacity as administrator of the Plan.

         AA. PRIOR PURCHASE AGREEMENT shall have the meaning assigned to such
term in Paragraph D.4.


                                      A-2.
<PAGE>   19

         AB. PURCHASED SHARES shall have the meaning assigned to such term in
Paragraph A.1.

         AC. RECAPITALIZATION shall mean any stock split, stock dividend,
recapitalization, combination of shares, exchange of shares or other change
affecting the Corporation's outstanding Common Stock as a class without the
Corporation's receipt of consideration.

         AD. REORGANIZATION shall mean any of the following transactions:

                  (i) a merger or consolidation in which the Corporation is not
         the surviving entity,

                  (ii) a sale, transfer or other disposition of all or
         substantially all of the Corporation's assets,

                  (iii) a reverse merger in which the Corporation is the
         surviving entity but in which the Corporation's outstanding voting
         securities are transferred in whole or in part to a person or persons
         different from the persons holding those securities immediately prior
         to the merger, or

                  (iv) any transaction effected primarily to change the state in
         which the Corporation is incorporated or to create a holding company
         structure.

         AE. REPURCHASE RIGHT shall mean the right granted to the Corporation in
accordance with Article D.

         AF. SEC shall mean the Securities and Exchange Commission.

         AG. SERVICE shall mean the Optionee's performance of services for the
Corporation (or any Parent or Subsidiary) in the capacity of an employee,
subject to the control and direction of the employer entity as to both the work
to be performed and the manner and method of performance, a non-employee member
of the board of directors or an independent consultant.

         AH. SUBSIDIARY shall mean any corporation (other than the Corporation)
in an unbroken chain of corporations beginning with the Corporation, provided
each corporation (other than the last corporation) in the unbroken chain owns,
at the time of the determination, stock possessing fifty percent (50%) or more
of the total combined voting power of all classes of stock in one of the other
corporations in such chain.

         AI. TARGET SHARES shall have the meaning assigned to such term in
Paragraph E.2.

         AJ. VESTING SCHEDULE shall mean the vesting schedule specified in the
Grant Notice pursuant to which the Optionee is to vest in the Option Shares in a
series of installments over his or her period of Service.

         AK. UNVESTED SHARES shall have the meaning assigned to such term in
Paragraph D.1.


                                      A-3.