Document:

Exhibit 4.1

THE WARRANTS REPRESENTED BY THIS CERTIFICATE AND THE SECURITIES ISSUABLE UPON
EXERCISE THEREOF HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 OR
THE SECURITIES OR BLUE SKY LAWS OF ANY STATE. NEITHER SUCH WARRANTS NOR SUCH
SECURITIES MAY BE SOLD, PLEDGED, HYPOTHECATED OR OTHERWISE TRANSFERRED WITHOUT
SUCH REGISTRATION, EXCEPT UPON DELIVERY TO THE COMPANY OF SUCH EVIDENCE AS MAY
BE SATISFACTORY TO COUNSEL FOR THE COMPANY TO THE EFFECT THAT ANY SUCH TRANSFER
SHALL NOT BE IN VIOLATION OF THE SECURITIES ACT OF 1933 OR APPLICABLE STATE
SECURITIES OR BLUE SKY LAWS OR ANY RULE OR REGULATION PROMULGATED THEREUNDER.

                          DISCOVERY LABORATORIES, INC.

                        Class F Warrant for the Purchase
                            of Shares of Common Stock

            FOR VALUE RECEIVED, DISCOVERY LABORATORIES, INC., a Delaware
corporation (the "Company"), hereby certifies that [     ] (the "Holder"), its
designee or its permitted assigns is entitled to purchase from the Company, at
any time or from time to time commencing on __________, 2001 and prior to 5:00
P.M., New York City time, on ________, 2006 up to [    ] ([    ]) fully paid and
non-assessable shares of Common Stock (subject to adjustment), $.001 par value
per share, of the Company for $[    ] per share (subject to adjustment as
provided herein) and an aggregate purchase price of $[    ]. (Hereinafter, (i)
said common stock, $.001 par value per share, of the Company, is referred to as
the "Common Stock," (ii) the shares of the Common Stock purchasable hereunder or
under any other Warrant (as hereinafter defined) are referred to as the "Warrant
Shares," (iii) the aggregate purchase price payable for the Warrant Shares
purchasable hereunder is referred to as the "Aggregate Warrant Price," (iv) the
price payable for each of the Warrant Shares is referred to as the "Per Share
Warrant Price," (v) this Warrant, all similar Warrants issued on the date hereof
and all warrants hereafter issued in exchange or substitution for this Warrant
or such similar Warrants are referred to as the "Warrants," and (vi) the holder
of this Warrant is referred to as the "Holder" and the holder of this Warrant
and all other Warrants and Warrant Shares are referred to as the "Holders" and
Holders of more than 50% of the outstanding Warrants and Warrant Shares are
referred to as the "Majority of the Holders"). The Aggregate Warrant Price is
not subject to adjustment.

            By acceptance of this Warrant, the Holder agrees to comply with all
applicable provisions of this Warrant and the Stock and Warrant Purchase
Agreement entered into between Holder and the Company (the "Purchase Agreement")
to the same extent as if it were a party thereto.

            1. Exercise of Warrant. (a) This Warrant may be exercised in whole
at any time, or in part from time to time, commencing on _______, 2001 and prior
to 5:00 P.M., Eastern Standard Time, on ________, 2006 by the Holder by the
surrender of this Warrant (with the

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subscription form at the end hereof duly executed) at the address set forth in
Section 10(a) hereof, together with proper payment of the Aggregate Warrant
Price, or the proportionate part thereof if this Warrant is exercised in part,
with payment for the Warrant Shares made by certified or official bank check
payable to the order of the Company; or

            (b) If this Warrant is exercised in part, this Warrant must be
exercised for a number of whole shares of the Common Stock and the Holder is
entitled to receive a new Warrant covering the Warrant Shares that have not been
exercised and setting forth the proportionate part of the Aggregate Warrant
Price applicable to such Warrant Shares.

            (c) Upon surrender of this Warrant, the Company will (i) issue a
certificate or certificates in the name of the Holder, or its nominee, for the
largest number of whole shares of the Common Stock to which the Holder shall be
entitled and, if this Warrant is exercised in whole, in lieu of any fractional
share of the Common Stock to which the Holder shall be entitled, pay to the
Holder cash in an amount equal to the fair value of such fractional share
(determined in such reasonable manner as the Board of Directors of the Company
(the "Board") shall determine), and (ii) deliver the other securities and
properties receivable upon the exercise of this Warrant, or the proportionate
part thereof if this Warrant is exercised in part, pursuant to the provisions of
this Warrant.

            2. Reservation of Warrant Shares; Listing. The Company agrees and
covenants that, prior to the expiration of this Warrant, the Company shall at
all times (i) have authorized and in reserve, and shall keep available, solely
for issuance and delivery upon the exercise of this Warrant, the shares of the
Common Stock and other securities and properties receivable upon the exercise of
this Warrant and shall be validly issued and non-assessable free and clear of
all restrictions on sale or transfer, other than under Federal or state
securities or blue sky laws, and free and clear of all preemptive rights and
rights of first refusal and (ii) use its best efforts to keep the Warrant Shares
authorized for listing on the Nasdaq National Market (the "National Market"),
the Nasdaq SmallCap Market (the "SmallCap Market") or any national securities
exchange on which the Company's Common Stock is traded.

            3. Protection Against Dilution.

                  (a) In the case the Company shall at any time after the date
of this Warrant (i) declare a dividend, or make a distribution, on the
outstanding Common Stock in shares of its Common Stock (ii) subdivide the
outstanding Common Stock, (iii) combine the outstanding Common Stock into a
smaller number of shares, or (iv) issue any shares of its capital stock by
reclassification of the Common Stock (including any such reclassification in
connection with a consolidation or merger in which the Company is the continuing
corporation), then, in each case, the Per Share Warrant Price, and the number
and kind of shares of Common Stock receivable upon exercise of this Warrant, in
effect as the time of the record date for such dividend or distribution or of
the effective date of such subdivision, combination, or reclassification, shall
be proportionately adjusted so that the Holder after such time shall be entitled
to receive the aggregate number and kind of shares which if such Warrant had
been exercised immediately prior to such time, it would have owned upon such
exercise and been entitled to receive by virtue of such dividend, distribution,
subdivision, combination or reclassification.

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                  (b) Intentionally Omitted.

                  (c) No adjustment in the Per Share Warrant Price shall be
required in the case of the issuance by the Company of Common Stock (i) pursuant
to the exercise of any warrant; or (ii) pursuant to the exercise of any stock
options or warrants currently outstanding or securities issued after the date
hereof, which may be approved by the Board pursuant to any Company benefit plan
or exercised, under any employee benefit plan of the Company to officers,
directors, consultants or employees.

                  (d) In case of any capital reorganization or reclassification,
or any consolidation or merger to which the Company is a party other than a
merger or consolidation in which the Company is the continuing corporation, or
in case of any sale or conveyance to another entity of the property of the
Company as an entirety or substantially as a entirety, or in the case of any
statutory exchange of securities with another corporation (including any
exchange effected in connection with a merger of a third corporation into the
Company), the Holder of this Warrant shall have the right thereafter to receive
upon the exercise of this Warrant the kind and amount of securities, cash or
other property which the Holder would have owned or have been entitled to
receive immediately after such reorganization, reclassification, consolidation,
merger, statutory exchange, sale or conveyance had this Warrant been exercised
immediately prior to the effective date of such reorganization,
reclassification, consolidation, merger, statutory exchange, sale or conveyance
and in any such case, if necessary, appropriate adjustment shall be made in the
application of the provisions set forth in this Section 3 with respect to the
rights and interests thereafter of the Holder of this Warrant to the end that
the provisions set forth in this Section 3 shall thereafter correspondingly be
made applicable, as nearly as may reasonably be, in relation to any shares of
stock or other securities or property thereafter deliverable on the exercise of
this Warrant. The above provisions of this Section 3(d) shall similarly apply to
successive reorganizations, reclassifications, consolidations, mergers,
statutory exchanges, sales or conveyances. The Company shall use its reasonable
best efforts to require the issuer of any shares of stock or other securities or
property thereafter deliverable on the exercise of this Warrant to be
responsible for all of the agreements and obligations of the Company hereunder.
Notice of any such reorganization, reclassification, consolidation, merger,
statutory exchange, sale or conveyance and of said provisions so proposed to be
made, shall be mailed to the Holders of the Warrants not less than ten (10) days
prior to such event. A sale of all or substantially all of the assets of the
Company for consideration consisting primarily of securities shall be deemed a
consolidation or merger for the foregoing purposes.

                  (e) No adjustment in the Per Share Warrant Price shall be
required unless such adjustment would require an increase or decrease of at
least $0.05 per share of Common Stock; provided, however, that any adjustments
which by reason of this Subsection 3(e) are not required to be made shall be
carried forward and taken into account in any subsequent adjustment; provided,
further, however, that adjustments shall be required and made in accordance with
the provisions of this Section 3 (other than this Subsection 3(e)) not later
than such time as may be required in order to preserve the tax-free nature of a
distribution to the Holder of this Warrant or Common Stock

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issuable upon the exercise hereof. All calculations under this Section 3 shall
be made to the nearest cent or to the nearest 1/100th of a share, as the case
may be. Anything in this Section 3 to the contrary notwithstanding, the Company
shall be entitled to make such reductions in the Per Share Warrant Price, in
addition to those required by this Section 3, as it in its discretion shall deem
to be advisable in order that any stock dividend, subdivision of shares or
distribution of rights to purchase stock or securities convertible or
exchangeable for stock hereafter made by the Company to its stockholders shall
not be taxable.

                  (f) Whenever the Per Share Warrant Price is adjusted as
provided in this Section 3 and upon any modification of the rights of a Holder
of Warrants in accordance with this Section 3, the Company shall promptly
prepare a brief statement of the facts requiring such adjustment or modification
and the manner of computing the same and cause copies of such certificate to be
mailed to the Holders of the Warrants. The Company may, but shall not be
obligated to unless requested by a Majority of the Holders, obtain, at its
expense, a certificate of a firm of independent public accountants of recognized
standing selected by the Board of Directors (who may be the regular auditors of
the Company) setting forth the Per Share Warrant Price and the number of Warrant
Shares in effect after such adjustment or the effect of such modification, a
brief statement of the facts requiring such adjustment or modification and the
manner of computing the same and cause copies of such certificate to be mailed
to the Holders of record of the Warrants.

                  (g) If the Board of Directors of the Company shall declare any
dividend or other distribution with respect to the Common Stock other than a
cash distribution out of earned surplus, the Company shall mail notice thereof
to the Holders of the Warrants not less than ten (10) days prior to the record
date fixed for determining stockholders entitled to participate in such dividend
or other distribution.

                  (h) If, as a result of an adjustment made pursuant to this
Section 3, the Holder of any Warrant thereafter surrendered for exercise shall
become entitled to receive shares of two or more classes of capital stock or
shares of Common Stock and other capital stock of the Company, the Board of
Directors (whose determination shall be conclusive and shall be described in a
written notice to the Holder of any Warrant promptly after such adjustment)
shall, in good faith, determine the allocation of the adjusted Per Share Warrant
Price between or among shares or such classes of capital stock or shares of
Common Stock and other capital stock.

                  (i) Upon the expiration of any rights, options, warrants or
conversion privileges with respect to the issuance of which an adjustment to the
Per Share Warrant Price had been made, if such shall not have been exercised,
the number of Warrant Shares purchasable upon exercise of this Warrant, to the
extent this Warrant has not then been exercised, shall, upon such expiration, be
readjusted and shall thereafter be such as they would have been had they been
originally adjusted (or had the original adjustment not been required, as the
case may be) on the basis of (A) the fact that Common Stock, if any, actually
issued or sold upon the exercise of such rights, options, warrants or conversion
privileges, and (B) the fact that such shares of Common Stock, if any, were
issued or sold for the consideration actually received by the Company upon such
exercise plus the consideration, if any, actually received by the Company for
the issuance, sale or grant of all

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such rights, options, warrants or conversion privileges whether or not
exercised; provided, however, that no such readjustment shall have the effect of
decreasing the number of Warrant Shares purchasable upon exercise of this
Warrant by an amount in excess of the amount of the adjustment initially made in
respect of the issuance, sale or grant of such rights, options, warrants or
conversion privileges.

                  (j) In case any event shall occur as to which the other
provisions of this Section 3 are not strictly applicable but as to which the
failure to make any adjustment would not fairly protect the purchase rights
represented by this Warrant in accordance with the essential intent and
principles hereof then, in each such case, the Board of Directors of the Company
shall in good faith determine the adjustment, if any, on a basis consistent with
the essential intent and principles established herein, necessary to preserve
the purchase rights represented by the Warrants. Upon such determination, the
Company will promptly mail a copy thereof to the Holder of this Warrant and
shall make the adjustments described therein.

            4. Fully Paid Stock; Taxes. The Warrant Shares delivered upon the
exercise of this Warrant shall at the time of such delivery, be duly authorized,
validly issued and outstanding, fully paid and non-assessable, and not subject
to preemptive rights or rights of first refusal, and the Company will take all
such actions as may be necessary to assure that the par value, if any, per
Warrant Shares is at all times equal to or less than the then Per Share Warrant
Price. The Company shall pay all documentary, stamp or similar taxes and other
similar governmental charges that may be imposed with respect to the issuance or
delivery of any Warrant Shares (other than income taxes); provided, however,
that if the Warrant Shares are to be delivered in a name other than the name of
the Holder, no such delivery shall be made unless the person requesting the same
has paid to the Company the amount of transfer taxes or charges incident
thereto, if any.

            5. Registration Under Securities Act of 1933. (a) The Holder shall
have the right to participate in the registration rights granted to Holders of
Registrable Securities (as defined in the Purchase Agreement) with respect to
the Warrant Shares.

            (b) Until all of the Warrant Shares have been sold under a
registration statement declared effective by the Securities and Exchange
Commission or pursuant to Rule 144, the Company shall use its best efforts to
file with the Securities and Exchange Commission all current reports and the
information as may be necessary to enable the Holder to effect sales of its
shares in reliance upon Rule 144 promulgated under the Securities Act of 1933
(the "Act").

            6. Investment Intent; Limited Transferability. (a) The Holder
represents, by accepting this Warrant, that it understands that this Warrant and
any securities obtainable upon exercise of this Warrant have not been registered
for sale under Federal or state securities or blue sky laws and are being
offered and sold to the Holder pursuant to one or more exemptions from the
registration requirements of such securities laws. In the absence of an
effective registration of such securities or an exemption therefrom, any
certificates for such securities shall bear the legend set forth on the first
page hereof. The Holder understands that it must bear the economic risk of its
investment in this Warrant and any securities obtainable upon exercise of this
Warrant for an

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<PAGE>

indefinite period of time, as this Warrant and such securities have not been
registered under Federal or state securities or blue sky laws and therefore
cannot be sold unless subsequently registered under such laws, unless an
exemption from such registration is available.

            (b) The Holder agrees and acknowledges that this Warrant and any
such securities will not be sold or otherwise transferred unless (i) a
registration statement with respect to such transfer is effective under the Act
and any applicable state securities or blue sky laws or (ii) such sale or
transfer is made pursuant to one or more exemptions from the Act.

            (c) The Holder agrees and acknowledges that in addition to the
limitations set forth in the Purchase Agreement with respect to Registrable
Securities, this Warrant may not be sold, transferred, assigned or hypothecated
by the Holder except in compliance with the provisions of the Act and the
applicable state securities or blue sky laws, and is so transferable only upon
the books of the Company which it shall cause to be maintained for such purpose.
The Company may treat the registered Holder of this Warrant as it appears on the
Company's books at any time as the Holder for all purposes. The Company shall
permit any Holder of a Warrant or its duly authorized attorney, upon written
request during ordinary business hours, to inspect and copy or make extracts
from its books showing the registered holders of Warrants. All Warrants issued
upon the transfer or assignment of this Warrant will be dated the same date as
this Warrant, and all rights of the holder thereof shall be identical to those
of the Holder.

            (d) The Holder represents that it has been afforded (i) the
opportunity to ask such questions as it has deemed necessary of, and to receive
answers from, representatives of the Company concerning the terms and conditions
of the Warrants or the exercise of the Warrants and the finance operations and
business of the Company; and (ii) the opportunity to request such additional
information which the Company possesses or can acquire without unreasonable
effort or expense. Nothing contained in this Section 6(d) shall alter, amend or
change Holder's reliance on the representations, covenants or warranties
contained herein.

            (e) The Holder represents that it did not (i) receive or review any
advertisement, article, notice or other communication published in a newspaper
or magazine or similar media or broadcast over television or radio, whether
closed circuit, or generally available; or (ii) attend any seminar, meeting or
investor or other conference whose attendees were, to such Holder's knowledge,
invited by any general solicitation or general advertising.

            (f) The Holder represents that it is an "accredited investor" within
the meaning of Regulation D promulgated under the Act. Such Holder is acquiring
the Warrants for its own account and not with a present view to, or for sale in
connection with, any distribution thereof in violation of the registration
requirements of the Act, without prejudice, however, to such Holder's right,
subject to the provisions of the Purchase Agreement and this Warrant, at all
times to sell or otherwise dispose of all or any part of the Warrants and
Warrant Shares.

            (g) The Holder represents that it, either by reason of such Holder's
business or financial experience or the business or financial experience of its
professional advisors (who are

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unaffiliated with and who are not compensated by the Company or any affiliate,
finder or selling agent of the Company, directly or indirectly), has such
sophistication, knowledge and experience in financial and business matters as to
be capable of evaluating the merits and risks of its investment in the Company
and the capacity to protect such Holder's interests in connection with the
transactions contemplated by this Warrant and the Purchase Agreement.

            (h) The Holder represents that it has the ability to bear the
economic risks of its investment for an indefinite period of time and could
afford a complete loss of its investment.

            (i) The Holder agrees and acknowledges that the representations made
by the Holder in this Section 6 are conditions to the exercise of the Warrant.

            7. Optional Redemption. In the event that the reported average
closing sales price of the Common Stock on the SmallCap Market at 4PM for any 20
trading days in any 30 consecutive trading-day-period is at least 300% of the
Per Share Warrant Price, the Company shall be entitled to redeem the Warrants,
or any of them, at a per Warrant redemption price of $0.001 (the "Redemption
Price"), upon 20 business-days' written notice to the Holder. Upon the
expiration of such 30 business-day-period, all Warrants noticed for redemption
that have not theretofore been exercised by the Holder shall, upon payment of
the aggregate Redemption Price therefore, cease to represent the right to
purchase any shares of Common Stock and shall be deemed cancelled and void and
of no further force or effect without any further act or deed on the part of the
Company. The Holder undertakes to return the certificate representing any
redeemed Warrants to the Company upon their redemption and to indemnify the
Company with respect to any losses, claims, damages or liabilities arising from
the Holder's failure to return such certificate. In the event the certificate so
returned represents a number of Warrants in excess of the number being redeemed,
the Company shall as promptly as practicable issue to the Holder a new
certificate for the number of unredeemed Warrants.

            8. Loss, etc., of Warrant. Upon receipt of evidence satisfactory to
the Company of the loss, theft, destruction or mutilation of this Warrant, and
of indemnity reasonably satisfactory to the Company, if lost, stolen or
destroyed, and upon surrender and cancellation of this Warrant, if mutilated,
the Company shall execute and deliver to the Holder a new Warrant of like date,
tenor and denomination.

            9. Warrant Holder Not Stockholder. This Warrant does not confer upon
the Holder any right to vote on or consent to or receive notice as a stockholder
of the Company, as such, in respect of any matters whatsoever, nor any other
rights or liabilities as a stockholder, prior to the exercise hereof; this
Warrant does, however, require certain notices to Holders as set forth herein.

            10. Communication. No notice or other communication under this
Warrant shall be effective unless, but any notice or other communication shall
be effective and shall be deemed to have been given if, the same is in writing
and is mailed by first-class mail, postage prepaid, addressed to:

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            (a) the Company at Discovery Laboratories, Inc., 350 South Main
            Street, Suite 307, Doylestown, Pennsylvania 18901, Attn: [Evan
            Myrianthopoulos, Vice President of Finance] or such other address as
            the Company has designated in writing to the Holder, or

            (b) the Holder at [       ], Attn: [       ] or other such address
            as the Holder has designated in writing to the Company.

            11. Headings. The headings of this Warrant have been inserted as a
matter of convenience and shall not affect the construction hereof.

            12. Applicable Law. This Warrant shall be governed by and construed
in accordance with the laws of the State of Delaware without giving effect to
the principles of conflicts of law thereof.

            13. Amendment, Waiver, etc. Except as expressly provided herein,
neither this Warrant 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 any provisions hereof may be amended, waived, discharged
or terminated upon the written consent of the Company and the Majority of the
Holders.

            IN WITNESS WHEREOF, the Company has caused this Warrant to be
executed this [    ] day of [     ], 2001.

                                     DISCOVERY LABORATORIES, INC.

                                     By:
                                         --------------------------------
                                     Name:  Robert J. Capetola, Ph.D.
                                     Title: President and
                                            Chief Executive Officer

                                       11
<PAGE>

                       (NOT PERMITTED UNTIL VESTING DATE)

                                  SUBSCRIPTION

            The undersigned, ___________________, pursuant to the provisions of
the foregoing Warrant, hereby elects to exercise such Warrant by agreeing to
subscribe for and purchase ____________________ shares (the "Warrant Shares") of
Common Stock, par value $.001 per share, of Discovery Laboratories, Inc. (the
"Company"), and hereby makes payment of $___________ by certified or official
bank check in payment of the exercise price therefor.

            As a condition to this subscription, the undersigned hereby
represents and warrants to the Company that the representations and warranties
of Section 6 of the Warrant are true and correct as of the date hereof as if
they had been made on such date with respect to the Warrant Shares. The
undersigned further acknowledges that the sale, transfer, assignment or
hypothecation of the Warrant Shares to be issued upon exercise of this Warrant
is subject to the terms and conditions contained in Sections 1 and 6 of this
Warrant.

Dated:_______________                       Signature:____________________

                                            Address:______________________
                                                    ______________________

                                   ASSIGNMENT

            FOR VALUE RECEIVED _______________ hereby sells, assigns and
transfers unto ____________________ the foregoing Warrant and all rights
evidenced thereby, and does irrevocably constitute and appoint
_____________________, attorney, to transfer said Warrant on the books of
Discovery Laboratories, Inc. (the "Company"). As a condition to this assignment,
the Holder acknowledges that its assignee must deliver a written instrument to
the Company that the representations and warranties of Section 6 of the Warrant
are true and correct as of the date hereof as if they had been made by such
assignee on such date with respect to the Warrants.

Dated:_______________                       Signature:____________________

                                            Address:______________________
                                                    ______________________

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<PAGE>

                               PARTIAL ASSIGNMENT

            FOR VALUE RECEIVED _______________ hereby assigns and transfers unto
____________________ the right to purchase _______ shares of the Common Stock,
par value $.001 per share, of Discovery Laboratories, Inc. (the "Company"), as
set forth in the foregoing Warrant, and a proportionate part of said Warrant and
the rights evidenced thereby, and does irrevocably constitute and appoint
____________________, attorney, to transfer that part of said Warrant on the
books of the Company. As a condition to this assignment, the Holder acknowledges
that its assignee must deliver a written instrument to the Company that the
representations and warranties of Section 6 of the Warrant are true and correct
as of the date hereof as if they had been made by such assignee on such date
with respect to the Warrants.

Dated:_______________                       Signature:____________________

                                            Address:______________________
                                                    ______________________

                                       13<PAGE>

                                                                    EXHIBIT 4.01

             FIFTH AMENDED AND RESTATED INVESTORS' RIGHTS AGREEMENT

     This Fifth Amended and Restated Investors' Rights Agreement (this
"Agreement") is made and entered into as of October __, 2001, by and among
NetScreen Technologies, Inc., a Delaware corporation (the "Company"), and the
persons and entities listed on Exhibit A attached hereto (the "Investors").
Comdisco, Inc. is a party to this Agreement for all purposes other than the
provisions of Sections 1 and 5 hereof. GATX Ventures, Inc. is a party to this
Agreement for all purposes other than the provisions of Sections 1, 2.2, 2.4, 3
and 5 hereof.

                                R E C I T A L S
                                ---------------

     A.   Certain of the Investors (the "Prior Investors") are holders of
outstanding shares of the Company's Series A Preferred Stock ("Series A Stock"),
Series B Preferred Stock ("Series B Stock"), Series C Preferred Stock ("Series C
Stock") Series D Preferred Stock ("Series D Stock") and/or Series E Preferred
Stock ("Series E Stock") issued by the Company to such Prior Investors pursuant
to Preferred Stock Purchase Agreements by and among the Company and the Prior
Investors (the "Prior Purchase Agreements"). The Prior Investors have been
granted certain information and registration rights and rights of first refusal
under a Fourth Amended and Restated Investors' Rights Agreement by and among the
Company and such Investors dated as of June 30, 2000, as amended by that certain
Amendment thereto dated February 28, 2001 (such agreement, as so amended the
"Prior Rights Agreement").

     B.   Certain Investors (the "Series F Investors") have agreed to purchase
shares of the Company's Series F Preferred Stock ("Series F Stock") pursuant to
a certain Series F Preferred Stock Purchase Agreement by and among the Company
and such Series F Investors dated of even date herewith(the "Series F
Agreement"). The Series F Agreement provides that, as a condition to the Series
F Investors' purchase of Series F Stock thereunder, the Company will enter into
this Agreement and the Series F Investors willbe granted the rights set forth
herein.

     C.   The Company and the undersigned parties hereto desire to enter into
this Agreement in order to amend, restate and replace their rights and
obligations under the Prior Rights Agreement with the rights and obligations set
forth in this Agreement. Section 4.2 of the Prior Rights Agreement provides that
the Prior Rights Agreement may be amended by the written consent of the holders
of a majority of the "Investors' Shares" (as defined in Section 4.2 of the Prior
Rights Agreement) and the undersigned parties to this Agreement hold a majority
of the Investors' Shares, as defined in the Prior Rights Agreement.

     NOW, THEREFORE, in consideration of the foregoing recitals and the mutual
 promises hereinafter set forth, the parties hereto agree as follows:

     1.   INFORMATION RIGHTS.
          ------------------

          1.1  Financial Information. The Company covenants and agrees that,
commencing on the date of this Agreement, for so long as any Investor holds at
least 120,000 shares of Preferred Stock and/or the equivalent number (on an
as-converted basis) of shares of

<PAGE>

Common Stock of the Company ("Common Stock") (together, the "Conversion Stock")
the Company will:

               (a)  Annual Reports. Furnish to such Investor, as soon as
practicable and in any event within 120 days after the end of each fiscal year
of the Company, a consolidated balance sheet of the Company and its subsidiaries
as of the end of such fiscal year, a consolidated statement of income and a
consolidated statement of cash flows of the Company and its subsidiaries for
such year, setting forth in each case in comparative form the figures from the
Company's previous fiscal year (if any), all prepared in accordance with
generally accepted accounting principles and practices and audited by nationally
recognized independent certified public accountants;

               (b)  Quarterly Reports. Furnish to such Investor as soon as
practicable, and in any case within thirty (30) days of the end after each
calendar quarter (except the last quarter of the Company's fiscal year),
quarterly unaudited financial statements, including an unaudited consolidated
balance sheet, and an unaudited consolidated statement of income and an
unaudited consolidated statement of cash flows of the Company and its
subsidiaries, with an instrument executed on behalf of the Company by the Chief
Financial Officer, Chief Executive Officer or President of the Company
certifying that such financial statements were prepared in accordance with
generally accepted accounting principles applied on a consistent basis, except
for the absence of normal audit adjustments and the absence of other supporting
statements, schedules and footnotes; and

               (c)  Annual Budget. Furnish to such Investor as soon as
practicable and in any event no later than thirty (30) days after the close of
each fiscal year of the Company, an annual operating plan and budget, prepared
on a monthly basis, for the next immediate fiscal year. The Company shall also
furnish to such Investor, within a reasonable time of its preparation,
amendments to the annual budget, if any.

          1.2  Inspection Rights. The Company shall permit each Investor holding
at least 400,000 shares of Preferred Stock and/or the equivalent number (on an
as-converted basis) of shares of Conversion Stock, or any combination thereof,
at such Investor's expense, to visit and inspect the Company's properties, to
examine its books of account and records and to discuss the Company's affairs,
finances and accounts with its officers, all at such reasonable times as may be
requested by such Investor.

          1.3  Confidentiality. Each Investor agrees to hold all information
received pursuant to this Section 1 in confidence, and not to use or disclose
any of such information to any third party for a period of two years from
receipt of the information in question, except to the extent (a) such
information may be made publicly available by the Company or (b) the disclosure
of such information is required by law (provided such Investor provides the
Company with prompt written notice so that the Company may seek a protective
order or other appropriate remedy).

          1.4  Termination of Certain Rights. The Company's obligations under
Sections 1.1 and 1.2 above will terminate upon the earlier to occur of (a) the
closing of the first

<PAGE>

public offering of Common Stock pursuant to an effective registration statement
filed under the Securities Act of 1933, as amended (the "1933 Act"), and (b) the
time at which the Company becomes subject to the reporting requirements of the
Securities Exchange Act of 1934, as amended (the "1934 Act"), other than in
connection with the Company's initial public offering.

     2.   REGISTRATION RIGHTS.
          -------------------

          2.1  Definitions. For purposes of this Section 2:

               (a)  Registration. The terms "register," "registered," and
"registration" refer to a registration effected by preparing and filing a
registration statement in compliance with the 1933 Act, and the declaration or
ordering of effectiveness of such registration statement.

               (b)  Registrable Securities. The term "Registrable Securities"
means: (i) all the shares of Common Stock of the Company issued or issuable upon
the conversion of any shares of Series A Stock, Series B Stock, Series C Stock,
Series D Stock, Series E Stock and Series F Stock; (ii) all the other shares of
Common Stock of the Company held from time to time by the Series F Investors;
(iii) all the shares of Common Stock directly or indirectly issuable upon
conversion or exercise of the warrants to purchase Series C Stock and Series D
Stock held by Comdisco, Inc. (which entity is deemed to be a party hereto); (iv)
all shares of Common Stock directly or indirectly issuable upon conversion or
exercise of the warrant to purchase 41,284 shares of Series E Stock held by GATX
Ventures, Inc.; and (v) any shares of Common Stock of the Company issued as (or
issuable upon the conversion or exercise of any warrant, right or other security
which is issued as) a dividend or other distribution with respect to, or in
exchange for or in replacement of, all such shares of Common Stock described in
clause (i) of this subsection (b) excluding in all cases, however, any
Registrable Securities sold by a person in a transaction in which rights under
this Section 2 are not assigned in accordance with this Agreement or any
Registrable Securities sold to the public or sold pursuant to Rule 144
promulgated under the 1933 Act.

               (c)  Registrable Securities Then Outstanding. The number of
shares of "Registrable Securities then outstanding" shall mean the number of
shares of Common Stock which are Registrable Securities and (i) are then issued
and outstanding; (ii) are then issuable pursuant to the exercise or conversion
of then outstanding and then exercisable options, warrants or convertible
securities; and (iii) are then issuable as a dividend or other distribution with
respect to, or in exchange for or in replacement of, all such shares of Common
Stock described in subsection (b)(i).

               (d)  Holder. For purposes of this Section 2 and Sections 3 and 4
hereof, the term "Holder" means (i) any person owning of record Registrable
Securities that have not been sold to the public or pursuant to Rule 144
promulgated under the 1933 Act or (ii) any assignee of record of such
Registrable Securities to whom rights under this Section 2 have been duly
assigned in accordance with this Agreement; provided, however, that for purposes
of this Agreement, a record holder of shares of Series A Stock, Series B Stock,
Series C Stock, Series D Stock, Series E Stock, or Series F Stock convertible
into such Registrable Securities shall be

<PAGE>

deemed to be the Holder of such Registrable Securities; and provided, further,
that the Company shall in no event be obligated to register shares of Series A
Stock, Series B Stock, Series C Stock, Series D Stock, Series E Stock, or Series
F Stock and that Holders of Registrable Securities will not be required to
convert their shares of Series A Stock, Series B Stock, Series C Stock, Series D
Stock, Series E Stock, or Series F Stock into Common Stock in order to exercise
the registration rights granted hereunder, until immediately before the closing
of the offering to which the registration relates.

               (e)  Form S-3. The term "Form S-3" means such form under the 1933
Act as is in effect on the date hereof or any successor registration form under
the 1933 Act subsequently adopted by the SEC which permits inclusion or
incorporation of substantial information by reference to other documents filed
by the Company with the SEC.

               (f)  SEC. The term "SEC" or "Commission" means the U.S.
Securities and Exchange Commission.

          2.2  Demand Registration.

               (a)  Request by Holders. If the Company shall receive at any time
after the earlier of (i) the third anniversary of this Agreement, or (ii) six
(6) months after the effective date of the Company's initial public offering of
its securities pursuant to a registration filed under the 1933 Act, a written
request from the Holders of at least twenty-five percent (25%) of the
Registrable Securities then outstanding that the Company file a registration
statement under the 1933 Act covering the registration of Registrable Securities
pursuant to this Section 2.2, then the Company shall, within ten (10) business
days of the receipt of such written request, give written notice of such request
("Request Notice") to all Holders, and effect, as soon as practicable, and in
any event within ninety (90) days after receipt of the request or requests of
the Initiating Holders (as defined below), the registration under the 1933 Act
of all Registrable Securities which Holders request to be registered and
included in such registration by written notice given by such Holders to the
Company within twenty (20) days after receipt of the Request Notice, subject
only to the limitations of this Section 2.2; provided that the Registrable
Securities requested by Holders to be registered pursuant to such request must
be at least twenty-five percent (25%) of all Registrable Securities then
outstanding (or any lesser percentage if the anticipated aggregate public
offering price equals or exceeds $5,000,000 (before deduction of underwriters'
discounts and commissions)).

               (b)  Underwriting. If the Holders initiating the registration
request under this Section 2.2 ("Initiating Holders") intend to distribute the
Registrable Securities covered by their request by means of an underwriting,
then they shall so advise the Company as a part of their request made pursuant
to this Section 2.2 and the Company shall include such information in the
written notice referred to in subsection 2.2(a). In such event, the right of any
Holder to include his Registrable Securities in such registration shall be
conditioned upon such Holder's participation in such underwriting and the
inclusion of such Holder's Registrable Securities in the underwriting (unless
otherwise mutually agreed by a majority in interest of the Initiating Holders
and such Holder) to the extent provided herein. All Holders proposing to
distribute their securities through such underwriting shall enter into an
underwriting agreement in

<PAGE>

customary form with the managing underwriter or underwriters selected for such
underwriting by the Company. Notwithstanding any other provision of this Section
2.2, if the underwriter(s) advise(s) the Company in writing that marketing
factors require a limitation of the number of securities to be underwritten then
the Company shall so advise all Holders of Registrable Securities which would
otherwise be registered and underwritten pursuant hereto, and the number of
Registrable Securities that may be included in the underwriting shall be reduced
as required by the underwriter(s) and allocated among the Holders of Registrable
Securities on a pro rata basis according to the number of Registrable Securities
then outstanding held by each Holder requesting registration (including the
Initiating Holders); provided, however, that the number of shares of Registrable
Securities to be included in such underwriting and registration shall not be
reduced unless all other securities of the Company are first entirely excluded
from the underwriting and registration. Any Registrable Securities excluded and
withdrawn from such underwriting shall be withdrawn from the registration.

               (c)  Maximum Number of Demand Registrations. The Company is
obligated to effect only two (2) registrations pursuant to this Section 2.2. A
registration shall not count toward such limit if the request for registration
is withdrawn by the Holders of a majority of the Registrable Securities sought
to be included in such registration and all expenses incurred in connection with
the registration are borne and reimbursed to the Company by the Holders making
the request for registration.

               (d)  Deferral. Notwithstanding the foregoing, if the Company
shall furnish to Holders requesting the filing of a registration statement
pursuant to this Section 2.2, a certificate signed by the President or Chief
Executive Officer of the Company stating that in the good faith judgment of the
Board of Directors of the Company, it would be seriously detrimental to the
business of the Company for such registration statement to be filed and it is
therefore essential to defer the filing of such registration statement, then the
Company shall have the right to defer such filing for a period of not more than
120 days after receipt of the request of the Initiating Holders; provided,
however, that the Company may not utilize this right more than once in any
twelve (12) month period. If the Company shall so delay the filing of a
registration statement, it shall promptly notify the applicable Holders of such
determination, and such Holders shall have the right to withdraw the relevant
request for registration, in which case such registration shall not count
towards the limit set forth in Section 2.2(c).

               (e)  Expenses. Other than as set forth in Section 2.2(c), All
expenses incurred in connection with a registration pursuant to this Section
2.2, including without limitation all registration and qualification fees,
printers' and accounting fees, fees and disbursements of counsel for the Company
(but excluding underwriters' discounts and commissions), shall be borne by the
Company. Each Holder participating in a registration pursuant to this Section
2.2 shall bear such Holder's proportionate share (based on the total number of
shares sold in such registration by such Holder other than for the account of
the Company) of all discounts, commissions or other amounts payable to
underwriters or brokers in connection with such offering. Notwithstanding the
foregoing, the Company shall not be required to pay for any expenses of any
registration proceeding begun pursuant to this Section 2.2 if the registration
request is subsequently withdrawn at the request of the Holders of a majority of
the Registrable Securities to be registered, unless the Holders of a majority of
the Registrable

                                        5

<PAGE>

Securities then outstanding agree to forfeit their right to one (1) demand
registration pursuant to this Section 2.2 (in which case such right shall be
forfeited by all Holders of Registrable Securities); provided, further, however,
that if at the time of such withdrawal, the Holders have learned of a material
adverse change in the condition, business, or prospects of the Company not known
to the Holders at the time of their request for such registration and have
withdrawn their request for registration with reasonable promptness after
learning of such material adverse change, then the Holders shall not be required
to pay any of such expenses and shall retain their rights pursuant to this
Section 2.2.

          2.3  Piggyback Registrations. The Company shall notify all Holders of
Registrable Securities in writing at least thirty (30) days prior to filing any
registration statement under the 1933 Act for purposes of effecting a public
offering of securities of the Company (including, but not limited to,
registration statements relating to secondary offerings of securities of the
Company, but excluding registration statements relating to any registration
under Section 2.2 or Section 2.4 of this Agreement or to any employee benefit
plan or a corporate reorganization or to an initial public offering of
securities of the Company for the Company's account) and will afford each such
Holder an opportunity to include in such registration statement all or any part
of the Registrable Securities then held by such Holder. Each Holder desiring to
include in any such registration statement all or any part of the Registrable
Securities held by such Holder shall, within twenty (20) days after receipt of
the above-described notice from the Company, so notify the Company in writing,
and in such notice shall inform the Company of the number of Registrable
Securities such Holder wishes to include in such registration statement. If a
Holder decides not to include all of its Registrable Securities in any
registration statement thereafter filed by the Company, such Holder shall
nevertheless continue to have the right to include any Registrable Securities in
any subsequent registration statement or registration statements as may be filed
by the Company with respect to offerings of its securities, all upon the terms
and conditions set forth herein.

               (a)  Underwriting. If a registration statement under which the
Company gives notice under this Section 2.3 is for an underwritten offering,
then the Company shall so advise the Holders of Registrable Securities as a part
of the notice referred to in this Section 2.3. In such event, the right of any
such Holder's Registrable Securities to be included in a registration pursuant
to this Section 2.3 shall be conditioned upon such Holder's participation in
such underwriting and the inclusion of such Holder's Registrable Securities in
the underwriting to the extent provided herein. All Holders proposing to
distribute their Registrable Securities through such underwriting shall enter
into an underwriting agreement in customary form with the managing underwriter
or underwriter(s) selected for such underwriting. Notwithstanding any other
provision of this Agreement, if the managing underwriter determine(s) in good
faith that marketing factors require a limitation of the number of shares to be
underwritten, then the managing underwriter(s) may exclude shares (including
Registrable Securities) from the registration and the underwriting, and the
number of shares that may be included in the registration and the underwriting
shall be allocated, first, to the Company, and second, to each of the Holders
requesting inclusion of their Registrable Securities in such registration
statement on a pro rata basis based on the total number of Registrable
Securities then held by each such Holder; provided however, that the right of
the underwriters to exclude shares (including Registrable Securities) from the
registration and underwriting as described above shall

                                       6

<PAGE>

be restricted so that the number of Registrable Securities included in any such
registration is not reduced below twenty-five percent (25%) of the shares
included in the registration, except for a registration relating to the
Company's initial public offering from which all Registrable Securities may be
excluded. If any Holder disapproves of the terms of any such underwriting, such
Holder may elect to withdraw therefrom by written notice to the Company and the
underwriter, delivered at least ten (10) business days prior to the effective
date of the registration statement. Any Registrable Securities excluded or
withdrawn from such underwriting shall be excluded and withdrawn from the
registration.

               (b)  Expenses. All expenses incurred in connection with the first
three registrations pursuant to this Section 2.3 (excluding underwriters' and
brokers' discounts and commissions), including, without limitation all federal
and "blue sky" registration and qualification fees, printers' and accounting
fees, fees and disbursements of counsel for the Company shall be borne by the
Company. All expenses incurred in connection with subsequent registrations
pursuant to this Section 2.3 shall be apportioned among, and borne by, the
Company and the participating Holders in the manner specified in Section 2.4(c).

          2.4  Form S-3 Registration. In case the Company shall receive from any
Holder or Holders of at least ten percent (10%) of all Registrable Securities
then outstanding a written request or requests that the Company effect a
registration on Form S-3 and any related qualification or compliance with
respect to all or a part of the Registrable Securities owned by such Holder or
Holders, then the Company will:

               (a)  Notice. Promptly give written notice of the proposed
registration and the Holder's or Holders' request therefor, and any related
qualification or compliance, to all other Holders of Registrable Securities; and

               (b)  Registration. As soon as practicable, effect such
registration and all such qualifications and compliances as may be so requested
and as would permit or facilitate the sale and distribution of all or such
portion of such Holder's or Holders' Registrable Securities as are specified in
such request, together with all or such portion of the Registrable Securities of
any other Holder or Holders joining in such request as are specified in a
written request given within twenty (20) days after receipt of such written
notice from the Company; provided, however, that the Company shall not be
obligated to effect any such registration, qualification or compliance pursuant
to this Section 2.4:

                    (i)   if Form S-3 is not available for such offering by the
Holders;

                    (ii)  if the Holders, together with the holders of any other
securities of the Company entitled to inclusion in such registration, propose to
sell Registrable Securities and such other securities (if any) at an aggregate
price to the public of less than $1,000,000;

                    (iii)  if the Company shall furnish to the Holders a
certificate signed by the President or Chief Executive Officer of the Company
stating that in the good faith

                                       7

<PAGE>

judgment of the Board of Directors of the Company, it would be seriously
detrimental to the business of the Company for such Form S-3 Registration to be
effected at such time, in which event the Company shall have the right to defer
the filing of the Form S-3 registration statement no more than once during any
twelve month period for a period of not more than 120 days after receipt of the
request of the Holder or Holders under this Section 2.4; provided, that, if the
Company shall so delay the filing of a registration statement, it shall promptly
notify the applicable Holders of such determination, and such Holders shall have
the right to withdraw the relevant request for registration, in which case such
registration shall not count towards the limit set forth in Section 2.4(b)(iv);

                    (iv)  if the Company has, within the twelve (12) month
period preceding the date of such request, already effected two (2)
registrations on Form S-3 for the Holders pursuant to this Section 2.4; or

                    (v)  in any particular jurisdiction in which the Company
would be required to qualify to do business or to execute a general consent to
service of process in effecting such registration, qualification or compliance.

Subject to the foregoing, the Company shall file a Form S-3 registration
statement covering the Registrable Securities and other securities so requested
to be registered pursuant to this Section 2.4 as soon as practicable, and in any
event no later than ninety (90) days, after receipt of the request or requests
of the Holders for such registration.

               (c)  Expenses. The Company shall pay all expenses incurred in
connection with the first registration requested pursuant to this Section 2.4 in
any given twelve-month period (excluding underwriters' or brokers' discounts and
commissions), including without limitation all filing, registration and
qualification, printers' and accounting fees and the reasonable fees and
disbursements of one (1) counsel for selling Holder or Holders and counsel for
the Company. For each registration for which the Company is obligated to pay
expenses pursuant to the preceding sentence, each Holder participating in such
registration shall bear such Holder's proportionate share (based on the number
of shares sold by such Holder over the total number of shares included in such
registration at the time it goes effective) of all discounts, commissions or
other amounts payable to underwriters or brokers in connection with such
offering. For each registration required pursuant to this Section 2.4 for which
the Company is not obligated to pay expenses pursuant to the first sentence of
this paragraph, all expenses incurred in connection with such registration shall
be borne by the Holders who participate in such registration on a pro rata
basis, and by the Company on a pro rata basis if it includes shares in such
registration, according to the number of Registrable Securities then owned by
the Holders and the number of shares offered by the Company that are included in
such registration at the time of its effectiveness.

               (d)  Not Demand Registration. Form S-3 registrations shall not be
deemed to be demand registrations as described in Section 2.2 above.

                                       8

<PAGE>

          2.5  Obligations of the Company. Whenever required to effect the
registration of any Registrable Securities under this Agreement, the Company
shall, as expeditiously possible:

               (a)  Prepare and file with the SEC a registration statement with
respect to such Registrable Securities and use its best efforts to cause such
registration statement to become effective, and, upon the request of the Holders
of a majority of the Registrable Securities registered thereunder, keep such
registration statement effective for at least one hundred eighty (180) days.

               (b)  Prepare and file with the SEC such amendments and
supplements to such registration statement and the prospectus used in connection
with such registration statement as may be necessary to comply with the
provisions of the 1933 Act with respect to the disposition of all securities
covered by such registration statement.

               (c)  Furnish to the Holders such number of copies of a
prospectus, including a preliminary prospectus, in conformity with the
requirements of the 1933 Act, and such other documents as they may reasonably
request in order to facilitate the disposition of the Registrable Securities
owned by them that are included in such registration.

               (d)  Use its best efforts to register and qualify the securities
covered by such registration statement under such other securities or Blue Sky
laws of such jurisdictions as shall be reasonably requested by the Holders,
provided that the Company shall not be required in connection therewith or as a
condition thereto to qualify to do business or to file a general consent to
service of process in any such states or jurisdictions.

               (e)  In the event of any underwritten public offering, enter into
and perform its obligations under an underwriting agreement, in usual and
customary form, with the managing underwriter(s) of such offering. Each Holder
participating in such underwriting shall also enter into and perform its
obligations under such an agreement.

               (f)  Notify each Holder of Registrable Securities covered by such
registration statement at any time when a prospectus relating thereto is
required to be delivered under the 1933 Act of the happening of any event as a
result of which the prospectus included in such registration statement, as then
in effect, includes an untrue statement of a material fact or omits to state a
material fact required to be stated therein or necessary to make the statements
therein not misleading in the light of the circumstances then existing.

               (g)  Furnish, at the request of any Holder requesting
registration of Registrable Securities, on the date that such Registrable
Securities are delivered to the underwriters for sale, if such securities are
being sold through underwriters, or, if such securities are not being sold
through underwriters, on the date that the registration statement with respect
to such securities becomes effective, (i) an opinion, dated as of such date, of
the counsel representing the Company for the purposes of such registration, in
form and substance as is customarily given to underwriters in an underwritten
public offering and reasonably satisfactory to a majority in interest of the
Holders requesting registration, addressed to the underwriters, if

                                       9

<PAGE>

any, and to the Holders requesting registration of Registrable Securities and
(ii) a "comfort" letter dated as of such date, from the independent certified
public accountants of the Company, in form and substance as is customarily given
by independent certified public accountants to underwriters in an underwritten
public offering and reasonably satisfactory to a majority in interest of the
Holders requesting registration, addressed to the underwriters, if any, and to
the Holders requesting registration of Registrable Securities.

          2.6  Furnish Information. It shall be a condition precedent to the
obligations of the Company to take any action pursuant to Sections 2.2, 2.3 or
2.4 that the selling Holders shall furnish to the Company such information
regarding themselves and the Registrable Securities held by them, and the
intended method of disposition of such securities as shall be required to timely
effect the registration of their Registrable Securities.

          2.7  Delay of Registration. No Holder shall have any right to obtain
or seek an injunction restraining or otherwise delaying any such registration as
the result of any controversy that might arise with respect to the
interpretation or implementation of this Section 2.

          2.8  Indemnification. In the event any Registrable Securities are
included in a registration statement under Sections 2.2, 2.3 or 2.4:

               (a)  By the Company. To the extent permitted by law, the Company
will indemnify and hold harmless each Holder, the partners, officers and
directors of each Holder, any underwriter (as defined in the 1933 Act) for such
Holder, each of their respective representatives and agents and such Holder's
legal counsel and independent accountants, and each person, if any, who controls
such Holder or underwriter within the meaning of the 1933 Act or the 1934 Act,
against any and all losses, claims, damages, or liabilities to which they may
become subject under the 1933 Act, the l934 Act or other federal or state law,
insofar as such losses, claims, damages, or liabilities (or actions in respect
thereof) arise out of or are based upon any of the following statements,
omissions or violations (each of the following being a "Violation"):

                   (i)   any untrue statement or alleged untrue statement of a
material fact contained in such registration statement, including any
preliminary prospectus or final prospectus contained therein, offering circular,
or other document or any amendments or supplements thereto incident to any such
registration, qualification or compliance;

                    (ii)  the omission or alleged omission to state therein a
material fact required to be stated therein, or necessary to make the statements
therein not misleading, or

                    (iii)  any violation or alleged violation by the Company of
the 1933 Act, the 1934 Act, any federal or state securities law or any rule or
regulation promulgated under the 1933 Act, the 1934 Act or any federal or state
securities law in connection with any action or inaction by the Company in
connection with the offering covered by such registration statement;

                                       10

<PAGE>

and the Company will reimburse each such Holder, partner, officer or director,
each of their respective representatives and agents and such Holder's legal
counsel and independent accountants, underwriter or controlling person for any
legal or other expenses reasonably incurred by them, as incurred, in connection
with investigating, preparing or defending any such loss, claim, damage,
liability or action; provided however, that the indemnity agreement contained in
this subsection 2.8(a) shall not apply to amounts paid in settlement of any such
loss, claim, damage, liability or action if such settlement is effected without
the consent of the Company (which consent shall not be unreasonably withheld or
delayed), nor shall the Company be liable in any such case for any such loss,
claim, damage, liability or action to the extent that it arises out of or is
based upon a Violation which occurs in reliance upon and in conformity with
written information furnished expressly for use in connection with such
registration by such Holder, partner, officer, director, underwriter or
controlling person of such Holder.

               (b)  By Selling Holders. To the extent permitted by law, each
selling Holder, severally but not jointly, if Registrable Securities held by
such Holder are included in the securities as to which such registration,
qualification or compliance is being effected, will indemnify and hold harmless
the Company, each of its directors, each of its officers who have signed the
registration statement, each person, if any, who controls the Company within the
meaning of the 1933 Act, any underwriter and any other Holder selling securities
under such registration statement or any of such other Holder's partners,
directors or officers, each of their respective representatives and agents and
such Holder's legal counsel and independent accountants, or any person who
controls such Holder within the meaning of the 1933 Act or the 1934 Act, against
any losses, claims, damages or liabilities (joint or several) to which the
Company or any such director, officer, controlling person, underwriter or other
such Holder, partner or director, officer or controlling person of such other
Holder may become subject under the 1933 Act, the 1934 Act or other federal or
state law, insofar as such losses, claims, damages or liabilities (or actions in
respect thereof) arise out of or are based upon any Violation under subsection
2.8(a)(i) or (ii), in each case to the extent (and only to the extent) that such
Violation under subsection 2.8(a)(i) or (ii) occurs in reliance upon and in
conformity with written information furnished by such Holder expressly for use
in connection with such registration; and each such Holder will reimburse any
legal or other expenses reasonably incurred by the Company or any such director,
officer, controlling person, underwriter or other Holder, partner, officer,
director or controlling person of such other Holder in connection with
investigating or defending any such loss, claim, damage, liability or action;
provided, however, that the indemnity agreement contained in this subsection
2.8(b) shall not apply to amounts paid in settlement of any such loss, claim,
damage, liability or action if such settlement is effected without the consent
of the Holder, which consent shall not be unreasonably withheld; and provided
further, that the total amounts payable in indemnity by a Holder under this
Section 2.8(b) in respect of any Violation under subsection 2.8(a)(i) or (ii)
shall not exceed the net proceeds received by such Holder in the registered
offering out of which such Violation under subsection 2.8(a)(i) or (ii) arises.

               (c)  Notice. Promptly after receipt by an indemnified party under
this Section 2.8 of notice of the commencement of any action (including any
governmental action), such indemnified party will, if a claim in respect thereof
is to be made against any indemnifying party under this Section 2.8, deliver to
the indemnifying party a written notice of the

                                       11

<PAGE>

commencement thereof and the indemnifying party shall have the right to
participate in, and, to the extent the indemnifying party so desires, jointly
with any other indemnifying party similarly noticed, to assume the defense
thereof with counsel mutually satisfactory to the parties; provided, however,
that an indemnified party shall have the right to retain its own counsel, with
the fees and expenses to be paid by the indemnifying party, if representation
of such indemnified party by the counsel retained by the indemnifying party
would be inappropriate due to actual or potential conflict of interests between
such indemnified party and any other party represented by such counsel in such
proceeding. The failure of any indemnified party to deliver written notice to
the indemnifying party within a reasonable time of the commencement of any such
action, only if such failure is prejudicial to its ability to defend such
action, shall relieve such indemnifying party of any liability to the
indemnified party under this Section 2.8, but the omission so to deliver
written notice to the indemnifying party will not relieve it of any liability
that it may have to any indemnified party otherwise than under this Section 2.8.
No indemnifying party, in the defense of any such claim or litigation, shall,
except with the consent of each indemnified party, consent to entry of any
judgment or enter into any settlement which does not include as an
unconditional term thereof the giving by the claimant or plaintiff to such
indemnified party of a release from all liability in respect of such claim or
litigation.

               (d)  Defect Eliminated in Final Prospectus. The foregoing
indemnity agreements of the Company and Holders are subject to the condition
that, insofar as they relate to any Violation made in a preliminary prospectus
but eliminated or remedied in the amended prospectus on file with the SEC at the
time the registration statement in question becomes effective or the amended
prospectus filed with the SEC pursuant to SEC Rule 424(b) (the "Final
Prospectus"), such indemnity agreement shall not inure to the benefit of any
person if a copy of the Final Prospectus was furnished to the indemnified party
and was not furnished to the person asserting the loss, liability, claim or
damage at or prior to the time such action is required by the 1933 Act.

               (e)  Contribution. In order to provide for just and equitable
contribution to joint liability under the 1933 Act in any case in which either
(i) any Holder exercising rights under this Agreement, or any controlling person
of any such Holder, makes a claim for indemnification pursuant to this Section
2.8 but it is judicially determined (by the entry of a final judgment or decree
by a court of competent jurisdiction and the expiration of time to appeal or the
denial of the last right of appeal) that such indemnification may not be
enforced in such case notwithstanding the fact that this Section 2.8 provides
for indemnification in such case, or (ii) contribution may be required on the
part of the Company and any such selling Holder or any such controlling person
in circumstances for which indemnification is provided under this Section 2.8;
then, and in each such case, such indemnifying party will contribute to the
aggregate losses, claims, damages or liabilities to which they may be subject
(after contribution from others) (i) in such proportion so that such Holder is
responsible for the portion represented by the percentage that the public
offering price of its Registrable Securities offered by and sold under the
registration statement bears to the public offering price of all securities
offered by and sold under such registration statement, and the Company and other
selling Holders are responsible for the remaining portion or (ii) if the
allocation provided by clause (i) above is not permitted by applicable law, in
such proportion as is appropriate to reflect not only the relative benefits
referred to in clause (i) above but also the relative fault of the Company and
the Holders in

                                       12

<PAGE>

connection with the statements or omissions that resulted in such losses,
claims, damages or liabilities, as well as any other relevant equitable
considerations. The relative fault of the Company and of the Holders shall be
determined by reference to, among other things, whether the untrue or alleged
untrue statement of a material fact or the omission or alleged omission to state
a material fact relates to information supplied by the Company or by the Holders
and the parties' relative intent, knowledge, access to information and
opportunity to correct or prevent such statement or omission. The Holders'
respective obligations to contribute pursuant to this Section are several in
proportion to the respective number of Registrable Securities they sell, and not
joint. No such Holder will be required to contribute any amount in excess of the
public offering price of all such Registrable Securities offered and sold by
such Holder pursuant to such registration statement; and no person or entity
guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of
the 1933 Act) will be entitled to contribution from any person or entity who was
not guilty of such fraudulent misrepresentation.

                (f)  Survival. The obligations of the Company and Holders under
this Section 2.8 shall survive the completion of any offering of Registrable
Securities in a registration statement, and otherwise.

           2.9  "Market Stand-Off" Agreement. Each Holder hereby agrees that it
shall not, to the extent requested by the Company or an underwriter of
securities of the Company, sell or otherwise transfer or dispose of any
Registrable Securities or other shares of stock of the Company then owned by
such Holder (other than to donees or partners of the Holder who agree to be
similarly bound) for up to one hundred eighty (180) days following the effective
date of a registration statement of the Company filed under the 1933 Act;
provided, however, that:

                (a)  such agreement shall be applicable only to the first such
registration statement of the Company which covers securities to be sold on its
behalf to the public in an underwritten offering but not to Registrable
Securities sold pursuant to such registration statement;

                (b)  all executive officers, directors and one percent
stockholders of the Company then holding Common Stock of the Company enter into
similar agreements; and

                (c)  any release of securities of the Company held by an
executive officer, director, one percent stockholder or Holder from such
agreement shall be effected between all executive officers, directors, one
percent stockholders and Holders on a pro rata basis according to the number of
shares of the Company's Common Stock then held by them.

           In order to enforce the foregoing covenant, the Company shall have
the right to place restrictive legends, substantially in the form set forth in
Section 5.3, on the certificates representing the shares subject to this Section
and to impose stop transfer instructions with respect to the Registrable
Securities and such other shares of stock of each Holder (and the shares or
securities of every other person subject to the foregoing restriction) until the
end of such period at which time the Company will, promptly upon request,
provide instructions to its transfer agent regarding the expiration of this
legend restriction.

                                       13

<PAGE>

          2.10 Rule 144 Reporting. With a view to making available the benefits
of certain rules and regulations of the Commission which may at any time permit
the sale of the Registrable Securities to the public without registration, after
such time as a public market exists for the Common Stock of the Company, the
Company agrees to:

               (a)  Make and keep public information available, as those terms
are understood and defined in Rule 144 under the 1933 Act, at all times after
the effective date of the first registration under the 1933 Act filed by the
Company for an offering of its securities to the general public;

               (b)  Use its best efforts to file with the Commission in a timely
manner all reports and other documents required of the Company under the 1933
Act and the 1934 Act (at any time after it has become subject to such reporting
requirements); and

               (c) So long as a Holder owns any Registrable Securities, to
furnish to the Holder forthwith upon request a written statement by the Company
as to its compliance with the reporting requirements of said Rule 144 (at any
time after 90 days after the effective date of the first registration statement
filed by the Company for an offering of its securities to the general public),
and of the 1933 Act and the 1934 Act (at any time after it has become subject to
the reporting requirements of the 1934 Act), a copy of the most recent annual or
quarterly report of the Company, and such other reports and documents of the
Company as a Holder may reasonably request in availing itself of any rule or
regulation of the Commission allowing a Holder to sell any such securities
without registration (at any time after the Company has become subject to the
reporting requirements of the 1934 Act).

          2.11 Termination of the Company's Obligations. The Company shall have
no obligations pursuant to Sections 2.2 through 2.4 with respect to: (a) any
request or requests for registration made by any Holder on a date more than five
(5) years after the first sale of the Common Stock to the public pursuant to an
effective registration statement filed by the Company under the 1933 Act,
provided that the Company is and continues to be subject to the reporting
requirements of the 1934 Act after such public offering; or (b) any Registrable
Securities proposed to be sold by a Holder in a registration pursuant to Section
2.2, 2.3 or 2.4 if, in the opinion of counsel to the Company, all such
Registrable Securities proposed to be sold by a Holder may be sold in a
three-month period without registration under the 1933 Act pursuant to Rule 144
under the 1933 Act.

     3.   RIGHT OF FIRST REFUSAL.

          3.1  General. Each Holder (as defined in Section 2.1(d)) owning not
less than 120,000 shares of either (i) Series A Stock, (ii) Series B Stock,
(iii) Series C Stock, (iv) Series D Stock, (v) Series E Stock or (vi) Series F
Stock and any party to whom such Holder's rights under this Section 3 have been
duly assigned in accordance with Section 4.1(b) (each such Holder or assignee
being hereinafter referred to as a "Rights Holder") has the right of first
refusal to purchase such Rights Holder's Pro Rata Share (as defined below), of
all (or any part) of any "New Securities" (as defined in Section 3.2) that the
Company may from time to time issue after the date of this Agreement; provided,
however, that such Rights Holder shall have no right

                                       14

<PAGE>

to purchase any such New Securities if such Rights Holder cannot demonstrate to
the Company's reasonable satisfaction that such Rights Holder is at the time of
the proposed issuance of New Securities an "accredited investor" as such term is
defined in Regulation D under the 1933 Act. A Rights Holder's "Pro Rata Share"
for purposes of this right of first refusal is the ratio of (a) the number of
Registrable Securities as to which such Rights Holder is the Holder (and/or is
deemed to be the Holder under Section 2.1(d)), to (b) a number of shares of
Common Stock of the Company equal to the sum of (i) the total number of shares
of Common Stock of the Company then outstanding plus (ii) the total number of
shares of Common Stock of the Company into which all then outstanding shares of
Preferred Stock of the Company are then convertible, plus (iii) the number of
shares of Common Stock of the Company reserved for issuance under any stock
purchase and stock option plans of the Company approved by the Company's Board
of Directors and outstanding warrants.

          3.2  New Securities. "New Securities" shall mean any capital stock of
the Company, whether now authorized or not, and rights, options or warrants to
purchase such capital stock, and securities of any type whatsoever that are, or
may become, convertible or exchangeable into such capital stock; provided,
however, that the term "New Securities" does not include:

               (i) any shares of the Company's Common Stock (and/or options or
warrants therefor) granted or issued to employees, officers, outside directors,
or consultants of the Company pursuant to written incentive agreements or plans
approved by the Board of Directors of the Company;

               (ii) any securities issuable upon conversion of or with respect
to any then outstanding shares of Series A Stock, Series B Stock, Series C
Stock, Series D Stock, Series E Stock, or Series F Stock or Common Stock or
other securities issuable upon conversion thereof;

               (iii) any securities issuable upon exercise of any options,
warrants or rights to purchase any securities of the Company outstanding on the
date of this Agreement and any securities issuable upon the conversion of any
such option, warrant or right;

               (iv)  shares of the Company's capital stock issued in connection
with any stock split or stock dividend or recapitalization;

               (v)   securities offered by the Company to the public pursuant to
a registration statement filed under the 1933 Act;

               (vi)  up to 600,000 shares of the Company's Common Stock and
Preferred Stock (and/or options or warrants therefor) issued or issuable to
parties providing the Company with equipment leases, real property leases,
loans, credit lines, guaranties of indebtedness, cash price reductions or
similar financing;

               (vii) up to 4,000,000 shares of capital stock issued pursuant to
the consolidation, merger, purchase of all or substantially all of the assets,
or other reorganization in

                                       15

<PAGE>

which the Company acquires, in a single transaction or series of related
transactions, all or substantially all of the assets of such other corporation
or entity or more than fifty percent (50%) or more of the voting power of such
other corporation or entity or more than fifty percent (50%) or more of the
equity ownership of such other entity; or

               (viii)  any shares of Series F Stock issued under the Series F
Agreement as such agreement may be amended.

          3.3  Procedures. In the event that the Company proposes to undertake
an issuance of New Securities, it shall give to each Rights Holder written
notice of its intention to issue New Securities (the "Notice"), describing the
type of New Securities and the price and the general terms upon which the
Company proposes to issue such New Securities. Each Rights Holder shall have
twenty (20) days from the date of mailing of any such Notice to elect in writing
to purchase such Rights Holder's Pro Rata Share of such New Securities for the
price and upon the general terms specified in the Notice by giving written
notice to the Company and stating therein the quantity of New Securities to be
purchased (not to exceed such Rights Holder's Pro Rata Share). If any Rights
Holder fails to so elect in writing within such twenty (20) day period to
purchase such Rights Holder's full Pro Rata Share of New Securities (a
"Nonpurchasing Holder"), then such Nonpurchasing Holder shall forfeit the right
hereunder to purchase that part of his Pro Rata Share of such New Securities
that he did not so agree to purchase and the Company shall promptly give each
Rights Holder who has timely elected to purchase his full Pro Rata Share of such
New Securities (a "Purchasing Holder") written notice of the failure of any
Nonpurchasing Holder to purchase such Nonpurchasing Rights Holder's full Pro
Rata Share of such offering of New Securities (the "Overallotment Notice"). Each
Purchasing Holder shall have a right of overallotment such that such Purchasing
Holder may agree to purchase a portion of the Nonpurchasing Holders' unpurchased
Pro Rata Shares of such offering on a pro rata basis according to the relative
Pro Rata Shares of the Purchasing Rights Holders, at any time within ten (10)
days after receiving the Overallotment Notice. If any Rights Holder notifies the
Company of its election to purchase such New Securities within such time period,
a closing with respect to such purchase shall be held at the principal office of
the Company (or at such other place as may be agreed upon by the Company and the
Rights Holder) on a date and at a time which are mutually agreeable to the
Company and such Rights Holder, but in no event later than the later to occur of
(a) sixty (60) days after receipt by the Company of such notice of the Rights
Holder's election and (b) ten (10) days after the receipt of any governmental
consent or approval necessary for the consummation of such transaction.

          3.4  Failure to Exercise. In the event that the Rights Holders fail to
exercise in full the right of first refusal within such twenty (20) plus ten
(10) day period, then the Company shall have ninety (90) days thereafter to sell
the New Securities with respect to which the Rights Holders' rights of first
refusal hereunder were not exercised, at a price and upon the same material
terms as specified in the Company's Notice to the Rights Holders. In the event
that the Company has not issued and sold the New Securities within such ninety
(90) day period, or offers to sell a lesser number of shares than specified in
such Notice, then the Company shall not thereafter issue or sell any New
Securities without again first offering such New Securities to the Rights
Holders pursuant to this Section 3.

                                       16

<PAGE>

          3.5 Termination. This right of first refusal shall terminate
immediately prior to the first to occur of: (a) the closing of the first sale of
Common Stock to the public pursuant to an effective registration statement filed
by the Company under the 1933 Act, (b) any reorganization, consolidation, merger
or similar transaction or series of related transactions (each, a "combination
transaction")) in which the Corporation is a constituent corporation or is a
party if, as a result of such combination transaction, the voting securities of
the Corporation that are outstanding immediately prior to the consummation of
such combination transaction (other than any such securities that are held by an
"Acquiring Stockholder", as defined below) do not represent, or are not
converted into, securities of the surviving corporation of such combination
transaction (or such surviving corporation's parent corporation if the surviving
corporation is owned by the parent corporation) that, immediately after the
consummation of such combination transaction, together possess at least a
majority of the total voting power of all securities of such surviving
corporation (or its parent corporation, if applicable) that are outstanding
immediately after the consummation of such combination transaction; and (c) a
sale of all or substantially all of the assets of the Corporation. For purposes
of this Section 3.5, an "Acquiring Stockholder" means a stockholder or
stockholders of the Company that (i) merges or combines with the Company in such
combination transaction or (ii) owns or controls a majority of another
corporation that merges or combines with the Company in such combination
transaction.

     4.   ASSIGNMENT AND AMENDMENT.

          4.1  Assignment. Notwithstanding anything herein to the contrary:

               (a)  Information Rights. The rights of an Investor under
Section 1.1 or 1.2 hereof may be assigned only to a party who acquires from an
Investor (or an Investor's permitted assigns) at least that number of shares of
Series A Stock, Series B Stock, Series C Stock, Series D, Series E Stock, and/or
Series F Stock and/or an equivalent number (on an as-converted basis) of shares
of Conversion Stock necessary to hold the rights described in Section 1.1 or 1.2
hereof, respectively.

               (b)  Registration Rights; Refusal Rights. The registration rights
of a Holder under Section 2 hereof and the rights of first refusal of a Rights
Holder under Section 3 hereof may be assigned only to an affiliate or a party
who acquires at least 120,000 shares of Series A Stock issued under the Series A
Agreement, 120,000 shares of Series B Stock issued under the Series B Agreement,
120,000 shares of Series C Stock issued under the Series C Agreement, 120,000
shares of Series D Stock issued under the Series D Agreement, 120,000 shares of
Series E Stock issued under the Series E Agreement, or 120,000 shares of Series
F Stock issued under the Series F Agreement or an equivalent number (on an
as-converted basis) of Registrable Securities issued upon conversion thereof;
provided, however that no party may be assigned any of the foregoing rights
unless the Company is given written notice by the assigning party at the time of
such assignment stating the name and address of the assignee and identifying the
securities of the Company as to which the rights in question are being assigned;
and provided further that any such assignee shall receive such assigned rights
subject to all the terms and conditions of this Agreement, including without
limitation the provisions of this Section 4.

                                       17

<PAGE>

               (c)  Aggregation. Shares of capital stock of the Company owned by
Investors, Holders and Rights Holders which are partnerships, limited liability
companies, corporations and other entities having substantially common ownership
interests or managed by the same principals or investment advisors or owned by
individual Investors affiliated with one another ("Affiliated Investors") shall
be aggregated for the purposes of this Agreement, and, notwithstanding anything
to the contrary contained in this Agreement, all rights granted to the
Investors, Holders and Rights Holders pursuant to this Agreement may be assigned
between Affiliated Investors. Without limiting the generality of the foregoing,
for purposes of this Section 4.1(c), (i) Spectrum Equity Investors IV, L.P. and
Spectrum IV Investment Managers' Fund, L.P. shall be deemed to be Affiliated
Investors, and (ii) Scudder Technology Innovation Fund and Scudder Technology
Fund shall be deemed to be Affiliated Investors.

          4.2  Amendment of Rights. Any provision of this Agreement may be
amended and the observance thereof may be waived (either generally or in a
particular instance and either retroactively or prospectively), only with the
written consent of the Company and Investors (and/or any of their permitted
successors or assigns) holding shares of Series A Stock, Series B Stock, Series
C Stock, Series D Stock, Series E Stock, and/or Series F Stock and/or Conversion
Stock representing and/or convertible into a majority of all the Investors'
Shares (as defined below); provided, however, that any amendment that directly
or indirectly (together with any transaction entered into in connection
therewith) treats any Holder or Holders in an adverse manner that is different
than any other Holders will require the approval of the Holders of a majority of
the Investors' Shares then held by such adversely treated Holders.
Notwithstanding the foregoing, the provisions of Section 5.7 may be amended and
the observance thereof may be waived (either generally or in a particular
instance and either retroactively or prospectively) only with the written
consent of GE Capital or its permitted assignee of the rights under Section 5.7
(without the need of written consent of any party other than the Company). As
used herein, the term "Investors' Shares" shall mean the shares of Common Stock
then issuable upon conversion of all then outstanding shares of Series A Stock,
shares of Series B Stock, shares of Series C Stock, shares of Series D Stock,
shares of Series E Stock, shares of Series F Stock, in each case held by
Investors and permitted assigns, plus all then outstanding shares of Conversion
Stock that were issued upon the conversion of any shares of Series A Stock
issued under the Series A Agreement, shares of Series B Stock issued under the
Series B Agreement, shares of Series C Stock issued under the Series C
Agreement, shares of Series D Stock issued under the Series D Agreement, shares
of Series E Stock issued under the Series E Agreement, or shares of Series F
Stock issued under the Series F Agreement, respectively, in each case held by
Investors and permitted assigns. Any amendment or waiver effected in accordance
with this Section 4.2 shall be binding upon each Investor, each Holder, each
Rights Holder, each permitted successor or assignee of such Investor or Holder
or Rights Holder and the Company.

          4.3  New Investors. Notwithstanding anything herein to the contrary,
if pursuant to Section 2.2 of the Series F Agreement, additional parties may
purchase shares of Series F Stock as "Investors" thereunder, then each such
Investor shall become a party to this Agreement as an "Investor" hereunder,
without the need of obtaining any consent, approval or signature of any Investor
when such Investor has both: (a) purchased shares of Series F Stock under the
Series F Agreement and paid the Company all consideration payable for such
shares

                                       18

<PAGE>

and (b) executed one or more counterpart signature pages to this Agreement as an
"Investor," with the Company's consent.

     5.   COVENANTS OF THE COMPANY
          ------------------------

          5.1  Reservation of Common Stock. The Company will at all times
reserve and keep available a sufficient number of shares of Common Stock for
issuance and delivery upon the conversion of the Series A Stock, Series B Stock,
Series C Stock, Series D Stock, Series E Stock and Series F Stock.

          5.2  Stock Vesting. All Common Stock issuances, stock options and
other stock equivalents granted or issued after the date of this Agreement to
employees, directors, consultants and other service providers, shall be made
from time to time under contracts, plans or other arrangements as recommended by
management and approved by the Company's Board of Directors and unless otherwise
approved by the Board of Directors, shall be subject to vesting as follows: (a)
twenty-five percent (25%) of such stock shall vest at the end of the first year
following the earlier of the date of grant or the commencement date of such
person's service with the Company, and (b) seventy-five percent (75%) of such
stock shall vest over the following three (3) years. With respect to any shares
of stock purchased by any such person, the Company's repurchase option shall
provide that upon such person's termination of employment or service with the
Company, with or without cause, the Company or its assignee (to the extent
permissible under applicable securities laws and other laws) shall have the
option to purchase at cost any unvested shares of stock held by such person.

          5.3  Legend. Each certificate representing Registrable Securities or
Preferred Stock convertible into Registrable Securities shall be stamped or
otherwise imprinted with a legend in the following form (in addition to any
legend required under applicable state securities laws):

     THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A MARKET STANDOFF
     AGREEMENT PURSUANT TO AN AGREEMENT BETWEEN THE ISSUER, THE REGISTERED
     HOLDER AND CERTAIN OTHER PARTIES. COPIES OF THE AGREEMENT RESTRICTING THEIR
     TRANSFER MAY BE OBTAINED AT NO COST BY WRITTEN REQUEST MADE BY THE HOLDER
     OF RECORD OF THIS CERTIFICATE TO THE SECRETARY OF THE CORPORATION AT THE
     PRINCIPAL EXECUTIVE OFFICES OF THE CORPORATION.

          5.4  Proprietary Information Agreements. The Company shall require the
execution of an Invention Assignment and Confidentiality Agreement, in the form
approved from time to time by the Company's Board of Directors, or a
substantially similar agreement, as a condition to hire for any officer,
director, employee, consultant, agent or contractor of the Company after the
date of this Agreement.

                                       19

<PAGE>

          5.5  Limitations on Subsequent Registration Rights. From and after the
date of this Agreement, the Company shall not, without the prior written consent
of Holder(s) of at least two-thirds (2/3) of the Registrable Securities then
outstanding, enter into any agreement with any holder or prospective holder of
any securities of the Company giving such holder or prospective holder any
registration rights the terms of which are equal to or more favorable than the
registration rights granted to Holders hereunder or requiring the Company to
effect a registration earlier than the date on which Holders can first require a
registration under Section 2.2; provided, however, that if such new agreement
does not affect all series of Preferred Stock in substantially the same manner,
approval must be obtained by majority vote of each series of Preferred Stock not
so affected.

          5.6  Directors' and Officers' Insurance. As soon as reasonably
possible, but in no event more than ninety (90) days after the date on which the
first share of Series F Stock is issued, the Company shall obtain and at all
times thereafter shall maintain in full force and effect, with financially sound
and reputable insurance companies, directors' and officers' insurance for a
coverage amount of at least $3,000,000 per occurrence on terms and conditions
that are approved by the Board; provided, however, that the Company shall not be
obligated by this Section 5.7 during such periods as the Board determines that
maintaining such coverage would be commercially unreasonable

          5.7  Attendance at Board Meetings.

               (a)  Board Observer Rights. For so long as General Electric
Capital Equity Investments, Inc. ("GE Capital") holds no less than 50% (fifty
percent) of the shares of the Series F Stock purchased by GE Capital pursuant to
the Series F Agreement and/or shares of Common Stock issued upon conversion
thereof, the Company will permit one representative of GE Capital to attend all
meetings of (i) Board and (ii) any executive or similar committee of the Board
and any other committee of the Board that the Board determines (from time to
time) is appropriate for attendance of such representative (any such committee,
a "Covered Committee"), in each case in a non-voting observer capacity;
provided, however, that such representative is subject to the approval by the
Board, such approval not to be unreasonably withheld; provided, further, that
any such representative must be an employee of GE Capital or its affiliates (or
an employee of any permitted assignee GE Capital of the rights under this
Section 5.8); and, provided, further, that the Company reserves the right not to
provide information and to exclude such representative from any meeting or
portion thereof if, in the Board's judgment, GE Capital or its representative
has a demonstrable conflict of interest with respect to the issue to be
discussed or the presence of the representative could jeopardize the Company's
attorney-client privilege. The Company agrees to provide GE Capital and any such
designated representative notice of all Board and Covered Committee meetings
contemporaneous with the giving of such notice, and in the same manner as such
notice is given, to members of the Board or the Covered Committee and, subject
to the last proviso in the foregoing sentence, to provide GE Capital and such
representative all information provided to members of the Board or Covered
Committee contemporaneous with providing such information to such members.

                                       20

<PAGE>

               (b)  Confidentiality. GE Capital agrees for a period of two years
from receipt of Confidential Information (i) to hold in strict confidence and to
act in a fiduciary manner with respect to all information and materials that it
may receive, or be given access to, in connection with meetings of the Board and
Covered Committees ("Confidential Information"), (ii) not to disclose any
Confidential Information to any third party, and (ii) not to use any
Confidential Information for any purpose detrimental to, or that may adversely
affect, the Company. GE Capital may disclose Confidential Information to GE
Capital's responsible employees, directors and/or officers and GE Capital's
lawyers, accountants and/or auditors with a bona fide need to know, and then
only to the extent necessary, and GE Capital agrees to instruct each such party
regarding the use and disclosure restrictions applicable to such Confidential
Information. GE Capital agrees to use its best efforts to cause its
representative to agree in writing to be similarly bound.

               (c)  Expenses. The Company shall reimburse all reasonable, direct
out-of-pocket travel, food and lodging expenses incurred by the GE Capital
representative in connection with his or her attendance of meetings of the Board
and any Covered Committee.

               (d)  Assignment. The rights described in this Section 5.7 may be
assigned only to a party who acquires from GE Capital no less than 50% (fifty
percent) of the shares of Series F Stock purchased by GE Capital pursuant to the
Series F Agreement; provided, however, that such rights may not be assigned to a
competitor of the Company (as determined by the Board in good faith); provided,
further, that no party may be assigned the foregoing rights unless the Company
is given the name and address of the assignee; provided, further, that, as a
condition precedent to acquiring such shares and the rights granted under this
Section 5.7, any such assignee shall be required first to agree in writing to be
bound by all the terms and conditions of this Section 5.7 and any representative
of such assignee shall similarly agree in writing.

          5.8  Assignment of Right of First Refusal. In the event that any
person or entity that is a "Stockholder" party to either that certain Second
Amended and Restated Co-Sale Agreement dated May 21, 1998, by and between the
Company and certain of its stockholders, or that certain Management Co-Sale
Agreement dated as of even date herewith, by and between the Company and certain
of its stockholders, as such agreements may be amended hereafter, proposes to
transfer shares of the Company's Common Stock that are subject to the Company's
right of first refusal under a restricted stock purchase agreement, stock option
exercise agreement, or similar agreement (each, a "Restricted Stock Agreement"),
then if the Company does not exercise such right of first refusal in full, the
Company shall give notice to the Rights Holders of such proposed disposition by
the selling Stockholder, including the terms thereof set forth in the selling
Stockholder's notice to the Company pursuant to the relevant Restricted Stock
Agreement, and specifying the number of shares that the Company will not acquire
(the "Remaining Shares") no later than ten (10) days after the Company's receipt
of notice of the proposed disposition from the selling Stockholder. Each Rights
Holder shall have seven (7) days after giving of such notice to give written
notice to the Company specifying the number of Remaining Shares that such Rights
Holder will acquire. The Company shall assign to each subscribing Rights Holder
such Rights Holder's Pro Rata Share of the unexercised portion of the

                                       21

<PAGE>

Company's right of first refusal. A Rights Holder's "Pro Rata Share" will be
determined by multiplying the number of Remaining Shares multiplied by a
fraction, the numerator of which is the number of shares of capital stock held
by the Rights Holder (determined on an as-converted to Common Stock basis), and
the denominator is the total number of shares of capital stock then held by all
Rights Holders (determined on an as-converted to Common Stock basis). If any
Rights Holder does not elect to purchase any shares (a "Nonpurchasing Rights
Holder"), the Company shall promptly give each Rights Holder who has timely
elected to purchase its full Pro Rata Share of Remaining Shares (a "Purchasing
Rights Holder") written notice of the failure of any Nonpurchasing Rights Holder
to purchase such Nonpurchasing Rights Holder's full Pro Rata Share of such
Remaining Shares (the "Overallotment Notice"). Each Purchasing Rights Holder
shall have a right of overallotment such that such Purchasing Rights Holder may
agree to purchase a portion of the Nonpurchasing Rights Holder's unpurchased Pro
Rata Share of such Remaining Shares on a pro rata basis according to the
relative Pro Rata Shares of the Purchasing Rights Holders, at any time within
seven (7) days after receiving the Overallotment Notice. The Company shall
assign to each subscribing Rights Holder the Company's right of first refusal
with respect to the Remaining Shares, with such assignments to be
proportionately made as set forth in this Section 5.8. Any exercise of the
assigned right of first refusal by an Investor or Investors shall be on the
terms set forth in the applicable Restricted Stock Agreement. The Company
represents and warrants to each Rights Holder that (i) the Company has the
valid, binding and enforceable right to acquire, at the Company's option, each
share of capital stock of the Company now held and proposed to be transferred by
each of the persons listed on Schedule 5.9 hereto (other than donative transfers
to family members or trusts for the benefit thereof as set forth in the
Restricted Stock Agreements), (ii) all of such rights are assignable by the
Company to the Rights Holders pursuant to this Section 5.8, (iii) the Company
has not granted any right, or otherwise entered into any agreement or
understanding, with respect to any capital stock subject to such rights that in
any respect conflicts with or impairs the rights of the Rights Holders hereunder
and (iv) upon any assignment of any such rights pursuant to this Section 5.8,
the Rights Holders will have the valid, binding and enforceable right to acquire
the shares of capital stock that are the subject of such assignment; provided,
however, that, the foregoing does not apply to the provisions of that certain
Stockholders' Agreement dated March 31, 1998, by and among the Company and
certain of its stockholders.

          5.9  Termination. The obligations of the Company under this Section 5
shall terminate immediately prior to the first to occur of: (a) the closing of
the first sale of Common Stock to the public pursuant to an effective
registration statement filed by the Company under 1933 Act provided that the
Company is subject to the reporting requirements of the Exchange Act immediately
after such closing; (b) the time at which the Company becomes subject to the
reporting requirements of the Exchange Act other than in connection with the
Company's initial public offering, (c) any reorganization, consolidation, merger
or similar transaction or series of related transactions (each, a "combination
transaction")) in which the Company is a constituent corporation or is a party
if, as a result of such combination transaction, the voting securities of the
Company that are outstanding immediately prior to the consummation of such
combination transaction (other than any such securities that are held by an
"Acquiring Stockholder", as defined below) do not represent, or are not
converted into, securities of the surviving corporation of such combination
transaction (or such surviving corporation's parent corporation if the

                                       22

<PAGE>

surviving corporation is owned by the parent corporation) that, immediately
after the consummation of such combination transaction, together possess at
least a majority of the total voting power of all securities of such surviving
corporation (or its parent corporation, if applicable) that are outstanding
immediately after the consummation of such combination transaction; and (d) a
sale of all or substantially all of the assets of the Company. For purposes of
this Section 5.9, an "Acquiring Stockholder" means a stockholder or stockholders
of the Company that (i) merges or combines with the Company in such combination
transaction or (ii) owns or controls a majority of another corporation that
merges or combines with the Company in such combination transaction

     6.   GENERAL PROVISIONS.
          ------------------

          6.1  Notices. Any and all notices required or permitted to be given to
a party pursuant to the provisions of this Agreement will be in writing and will
be effective and deemed to provide such party sufficient notice under this
Agreement on the earliest of the following: (i) at the time of personal
delivery, if delivery is in person; (ii) one (1) business day after deposit with
an express overnight courier for United States deliveries, or three (3) business
days after such deposit for deliveries outside of the United States, with proof
of delivery from the courier requested; or (iii) three (3) business days after
deposit in the United States mail by certified mail (return receipt requested)
for United States deliveries.

          All notices for delivery outside the United States will be sent by
express courier. All notices not delivered personally will be sent with postage
and/or other charges prepaid and properly addressed to the party to be notified
at the address as follows, or at such other address as such other party may
designate by one of the indicated means of notice herein to the other parties
hereto as follows:

               (a)  if to an Investor, at such Investor's respective address as
set forth on Exhibit A hereto; and

               (b)  if to the Company, marked "Attention: President", at 350
Oakmead Parkway, Sunnyvale, California 94085.

          6.2  Entire Agreement. This Agreement, together with all the Exhibits
hereto, constitutes and contains the entire agreement and understanding of the
parties with respect to the subject matter hereof and supersedes any and all
prior negotiations, correspondence, agreements, understandings, duties or
obligations between the parties respecting the subject matter hereof. Any
previous agreement between the Company and any Investor concerning Registration
rights including the Prior Rights Agreement, is superseded.

          6.3  Governing Law. This Agreement shall be governed by and construed
exclusively in accordance with the internal laws of the State of California as
applied to agreements among California residents entered into and to be
performed entirely within California, excluding that body of law relating to
conflict of laws and choice of law.

                                       23

<PAGE>

          6.4  Severability. If one or more provisions of this Agreement are
held to be unenforceable under applicable law, then such provision(s) shall be
excluded from this Agreement and the balance of this Agreement shall be
interpreted as if such provision(s) were so excluded and shall be enforceable in
accordance with its terms.

          6.5  Third Parties. Nothing in this Agreement, express or implied, is
intended to confer upon any person, other than the parties hereto and their
successors and assigns, any rights or remedies under or by reason of this
Agreement.

          6.6  Successors And Assigns. Subject to the provisions of Section 4.1,
the provisions of this Agreement shall inure to the benefit of, and shall be
binding upon, the successors and permitted assigns of the parties hereto.

          6.7  Captions. The captions to sections of this Agreement have been
inserted for identification and reference purposes only and shall not be used to
construe or interpret this Agreement.

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

          6.9  Costs And Attorneys' Fees. In the event that any action, suit or
other proceeding is instituted concerning or arising out of this Agreement or
any transaction contemplated hereunder, the prevailing party shall recover all
of such party's costs and attorneys' fees incurred in each such action, suit or
other proceeding, including any and all appeals or petitions therefrom.

          6.10 Adjustments for Stock Splits, Etc. Wherever in this Agreement
there is a reference to a specific number of shares of Common Stock or Preferred
Stock of the Company of any class or series, then, upon the occurrence of any
subdivision, combination or stock dividend of such class or series of stock
occurring after the date of this Agreement, the specific number of shares so
referenced in this Agreement shall automatically be proportionally adjusted to
reflect the affect on the outstanding shares of such class or series of stock by
such subdivision, combination or stock dividend.

          6.11 Approval of Amendments and Waiver of Rights of First Refusal.
Each Prior Investor hereby consents with respect to all shares of capital stock
held by such Investor to (a) the amendment and restatement of the Prior Rights
Agreement, and (b) the waiver of the Company's obligations, the notice period
and the rights of first refusal of certain Prior Investors under Section 3 of
the Prior Rights Agreement with respect to the issuance of the Series F Stock to
be issued under the Series F Agreement, as such agreement may be amended.

          6.12 Waiver of Jury Trial. Each party hereto hereby waives its rights
to a jury trial of any claim or cause of action based upon or arising out of
this Agreement or the subject matter hereof. The scope of this waiver is
intended to be all-compassing of any and all disputes that may be filed in any
court and that relate to the subject matter of this transaction, including,

                                       24

<PAGE>

without limitation, contract claims, tort claims, breach of duty claims, and all
other common law and statutory claims. This Section 6.12 has been fully
discussed by each of the parties hereto and these provisions shall not be
subject to any exceptions. Each party hereto hereby further warrants and
represents that such party has reviewed this waiver with its legal counsel, and
that such party knowingly and voluntarily waives its jury trial rights following
consultation with legal counsel. This waiver is irrevocable, meaning that it may
not be modified either orally or in writing, and this waiver shall apply to any
subsequent amendments, supplements or modifications to (or assignments of) this
Agreement. In the event of litigation, this Agreement may be filed as a written
consent to a trial (without a jury) by the court.

                  [Remainder of page intentionally left blank.]

                                       25

<PAGE>

                                   EXHIBIT A
                                   ---------

                              Schedule of Investors

Investor
--------
GE Capital Equity Investments, Inc.
120 Long Ridge Road
Stamford, CT 06977
Attention:   NetScreen Technologies, Inc.
             Account Manager; and
             General Counsel

Scudder Technology Innovation Fund
c/o Zurich Scudder Investments, Inc.
345 Park Avenue
New York, NY 10154
Attention: General Counsel

Scudder Technology Fund
c/o Zurich Scudder Investments, Inc.
345 Park Avenue
New York, NY 10154
Attention: General Counsel

Capital Guardian US Small Capitalization Fund
(Private Placement Eligible) for Tax Exempt Trusts
c/o Capital Guardian Trust Company
630 Fifth Avenue, 36th Floor
New York, NY 10111-0121
Attention: Suzanne Stewart

With a copy to:

c/o Capital Guardian Trust Company
11100 Santa Monica Blvd., 15th Floor
Los Angeles, CA 90025-3384
Attention: Mark Brubaker

<PAGE>

Capital Guardian US Small Capitalization Master
Fund (Private Placement Eligible)
c/o Capital Guardian Trust Company
630 Fifth Avenue, 36th Floor
New York, NY 10111-0121
Attention: Suzanne Stewart

With a copy to:

c/o Capital Guardian Trust Company
11100 Santa Monica Blvd., 15th Floor
Los Angeles, CA 90025-3384
Attention: Mark Brubaker

Pennsylvania Public School Employees'
Retirement System
c/o Capital Guardian Trust Company
630 Fifth Avenue, 36th Floor
New York, NY 10111-0121
Attention: Suzanne Stewart

With a copy to:

c/o Capital Guardian Trust Company
11100 Santa Monica Blvd., 15th Floor
Los Angeles, CA 90025-3384
Attention: Mark Brubaker

SMALLCAP World Fund, Inc.
c/o Capital Research and Management Company
333 South Hope Street
Los Angeles, CA 90071-1447
Attention: Mike Downer

Spectrum Equity Investors IV, L.P.
Spectrum IV Investment Managers' Fund, L.P.
333 Middlefield Road, Suite 200
Menlo Park, CA 94025
Attention: Victor E. Parker

<PAGE>

Sequoia Capital VII
Sequoia Capital Franchise Fund
Sequoia Capital Franchise Partners
Sequoia Technology Partners VII
Sequoia International Partners
Sequoia 1997 LLC
SQP 1997
3000 Sand Hill Road
Bldg. 4, Suite 280
Menlo Park, CA 94025
Attention: Michael Goguen

Techgains Corporation
Techgains Pan Pacific Corporation
Techgains International Corporation
1111 Jupiter Rd. Suite 100B
Plano, TX 75074
Attention: Andrew Kang
Contact: Lolly Li (li@tamcfund.com)

Silicon Valley Equity Fund, L.P.
Silicon Valley Equity Fund II, L.P.
2041 Mission College Boulevard
Suite 100
Santa Clara, CA 95054
Attention: Katherine Jen

Technology Partners Venture Capital Corp.
2F-2, 130, Szu-Wei Road
Hsinchu, Taiwan

Masaharu Shinya
Global Alliance Inc.
4-5, Tsukiji 1-Chome
Chuo-ku
Tokyo, 104-0045 Japan

KJL Investment
Chiu Family Living Trust
Chiu Family Children's Trust
Chiu Family Charitable Remainder Unitrust
19163 Via Tesoro Court
Saratoga, CA 95070

<PAGE>

E92 Plus Group, PLC
St. James House
St James Road
Surbiton Surrey KTG 4QH
United Kingdom

Hitachi Seibu Software, Ltd.
Hitachi Systems & Services, Ltd.
4-16, Uchihonmachi 2-chome, Chuo-ku
Osaka, 540-0026, Japan

EICO, Inc.
1054 Yosemite Drive
Milpitas, CA 95035

PJ&K Investments Corporation
2F-2, No. 130, Szu-Wei Road
Hsinchu, Taiwan

Nahil Sifri
2250, Place Transcanadienne
Dorval, (Quebec) H9P 2X5

Congress Communications, PLC
Wilshire House 19/21 Woolmead
Farnham Surrey GU9 OSJ
United Kingdom

Netsoft Associates
2727 Walsh Ave. Suite 101
Santa Clara, CA 95051

F & W Investments LLC
Two Palo Alto Square
Palo Alto, CA 94306

SecureSoft, Inc.
9th Floor, Doosan B/D,
105-7 Nonhyun-Dong,
Kangnam-Ku, Seoul, Korea

<PAGE>

Case Technology, S.A.
Isla Del Hierro No.5,
28700 S.S. de Los Reyes, Madrid
Spain

Paul Gupta
15000 Blue Gum Court
Saratoga, CA 95070

Big Basin Partners, L.P.
14585 Big Basin Way
Saratoga, CA 95070

David C. Weng Living Trust
1101 Di Napoli Drive
San Jose, CA 95129

Sumitomo Corporation Tokyo
2-2, Hitotsubashi 1Chome
Chiyoda-ku, Tokyo
100-8601, Japan
Attn. Mr. Daisuke Mikogami
with a copy to:
Sumitomo Corporation of America
600 3rd Ave.
New York, New York 10016-2001
Attn. Mr. William Fornshell

TEKKANG Management Consulting Inc.
1111 S. Sherman Street #101
Richardson, TX 75081
Attention: Andrew Kang

Thomas F. and Kathy S. Mendoza
c/o Network Appliance, Inc.
495 East Java Drive
Sunnyvale, CA 94089

Hsun Kwei Chou and Aiko Chou Trust
13211 West Sunset Drive
Los Altos Hills, CA 94022

<PAGE>

MCI WorldCom Venture Fund, Inc.
1801 Pennsylvania Ave, NW
Washington DC 20006
Attn: Susan Mayer

Ericsson Holding International B.V.
77 South Bedford St.
Burlington, Massachusetts 01803
Attn: Jeff Low

Snaiso
141 Avenue de Veroun
92130 Issy-Les-Moolineaux
France

Daniel Gutenberg
Gutenberg Communications Systems AG
Hardturmstr. 101, CH-8005 Zurich

Equinox Solutions Through Partnership Ltd.
Equinox House
25 Invincible Rd
Farnborough, Hampshire GU14 7QU

Presidio Venture Partners
2900 Patrick Henry Drive
Santa Clara CA 95054
Attn: Ike Nakamura

Juniper Networks, Inc.
1194 North Mathilda Avenue
Sunnyvale, CA 94089
ATTN: Rob Atherton

Datalink Business Solutions Ltd.
C1, 1F Phase 1,
Kaiser Estate
41 Man Yue St.
Hunghom Kowloon
Hong Kong

Cheng-FengChen

<PAGE>

7th Floor, Room 3
#21, Sec. 2 Chung King So. Rd.
Taipei, Taiwan, ROC

Deacon Family Trust
884 Santa Rita Ave.
Los Altos, CA 94022

Hongping Zhang
3615 Rue Mirassou
San Jose, CA 95148

Michael M.C. Chiu
19163 Via Tesoro Ct.
Saratoga, CA 95070

CLAS Investment
4138 Remillard Court
Pleasanton, CA 94566
Attn: Shinnan Kiang

Yi-Chih Hans Tai
No. 4-1 Kou-Hwa Street
Hsinchu, Taiwan

Inkeun Lee
4701 NE Shore Place
Lake Forest Park, WA 98155

M. Liu Trust
1255 Post Street, Suite 840
San Francisco, CA 94109

Hien Ngoc Truong
1281 Arizona Ave.
Milpitas, CA 95035

Alex Chang
6048 Crossview Circle
San Jose, CA 95120

<PAGE>

Godfrey Fong
12291 Barley Hill Road
Los Altos Hill, CA 94022

Comdisco, Inc.
6111 North River Road
Rosemount, Illinois 60018
Attention: Venture Lease Administration
Attention: Legal Department General Counsel

GATX Ventures, Inc.

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