Document:

<PAGE>   1
                                                                    EXHIBIT 4.20

                               CLASS C CERTIFICATE

                             REGISTERED $151,439,000
                          Fractional Undivided Interest
                                    No. R - 1
                              CUSIP NO. 909317 AX 7

         UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO THE TRUSTEE OR
ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE
ISSUED IN EXCHANGE FOR THIS CERTIFICATE IS REGISTERED IN THE NAME OF CEDE & CO.
OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC
(AND ANY PAYMENT HEREON IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER
USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS
THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

         TRANSFERS OF THIS CERTIFICATE SHALL BE LIMITED TO TRANSFERS IN WHOLE,
BUT NOT IN PART, TO NOMINEES OF DTC OR TO A SUCCESSOR THEREOF OR SUCH
SUCCESSOR'S NOMINEE AND TRANSFERS OF PORTIONS OF THIS CERTIFICATE SHALL BE
LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN
SECTIONS 3.05 AND 3.06 OF THE PASS THROUGH TRUST AGREEMENT REFERRED TO HEREIN.

         EITHER: (A) THE HOLDER IS NOT ACQUIRING THIS CERTIFICATE OR AN INTEREST
HEREIN WITH PLAN ASSETS OF ANY PLAN OR AN INDIVIDUAL RETIREMENT PLAN SUBJECT TO
TITLE I OF THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974, AS AMENDED
("ERISA"), OR SECTION 4975 OF THE INTERNAL REVENUE CODE OF 1986, AS AMENDED (THE
"CODE"); OR (B) THE HOLDER'S PURCHASE AND HOLDING OF THIS CERTIFICATE OR AN
INTEREST HEREIN IS EXEMPT FROM THE PROHIBITED TRANSACTION RESTRICTIONS OF
SECTION 406(A) OF ERISA AND SECTION 4975 OF THE CODE BY AN ADMINISTRATIVE CLASS
PROHIBITED TRANSACTION EXEMPTION GRANTED BY THE DEPARTMENT OF LABOR.

<PAGE>   2

               UNITED AIRLINES 2000-2C ENHANCED PASS THROUGH TRUST

                      UNITED AIRLINES ENHANCED PASS THROUGH
                           CERTIFICATE, SERIES 2000-2C

            Final Expected Regular Distribution Date: October 1, 2005

evidencing a fractional undivided interest in a trust, the property of which
includes certain equipment notes each secured by an Aircraft owned by United Air
Lines, Inc.

         THIS CERTIFIES THAT CEDE & CO., for value received, is the registered
owner of a ONE HUNDRED FIFTY-ONE MILLION FOUR HUNDRED THIRTY-NINE THOUSAND
DOLLAR ($151,439,000) Fractional Undivided Interest in the United Airlines
2000-2C Pass Through Trust (the "Trust") created by State Street Bank and Trust
Company of Connecticut, National Association, as trustee (the "Trustee")
pursuant to a Pass Through Trust Agreement, dated as of December 14, 2000 (the
"Basic Agreement"), as supplemented by Trust Supplement No. 2000-2C
(collectively, the "Agreement") between the Trustee and United Air Lines, Inc.,
a Delaware corporation (the "Company"), a summary of certain of the pertinent
provisions of which is set forth below. To the extent not otherwise defined
herein, the capitalized terms used herein have the meanings assigned to them in
the Agreement. This Certificate is one of the duly authorized Certificates
designated as "United Airlines Enhanced Pass Through Certificates, Series
2000-2C" (the "Certificates"). This Certificate is issued under and is subject
to the terms, provisions and conditions of the Agreement.

         By virtue of its acceptance hereof, the Certificateholder of this
Certificate assents to and agrees to be bound by the provisions of the
Agreement, the Intercreditor Agreement and the Note Purchase Agreement. The
property of the Trust includes (i) certain Notes and all monies at any time paid
thereon and all monies due and to become due thereunder, (ii) funds from time to
time deposited in the related Escrow Account, the related Certificate Account
and the related Special Payments Account, (iii) all rights of such Trust and the
Trustee, on behalf of such Trust, under the Intercreditor Agreement and the Note
Purchase Agreement, including all rights to receive certain payments thereunder
and all monies paid to such Trustee on behalf of such Trust pursuant to the
Intercreditor Agreement and the Note Purchase Agreement and (iv) all monies
receivable by the Subordination Agent under the Liquidity Facility for the Trust
(the "Trust Property"). Each issue of the Notes is secured directly or
indirectly by, among other things, a security interest in the Aircraft owned by
the Company.

         The Certificates represent Fractional Undivided Interests in the Trust
and the Trust Property, and have no rights, benefits or interest in respect of
any assets or property of any trust of another class.

         Interest applicable to this Certificate will be payable at a rate equal
to 7.762%.

         Subject to and in accordance with the terms of the Agreement, the
Intercreditor Agreement and the Note Purchase Agreement, from and to the extent
of funds then available to

<PAGE>   3

the Trustee, there shall be distributed on each April 1 and October 1 (a
"Regular Distribution Date"), commencing on April 1, 2001, to the Person in
whose name this Certificate is registered at the close of business on the 15th
day preceding such Regular Distribution Date, an amount in respect of the
Scheduled Payments on the Notes due on such Regular Distribution Date, the
receipt of which has been confirmed by the Trustee, equal to the product of the
percentage interest in the Trust evidenced by this Certificate and an amount
equal to the sum of such Scheduled Payments. Subject to and in accordance with
the terms of the Agreement, the Intercreditor Agreement and the Note Purchase
Agreement, if Special Payments on the Notes are received by the Trustee, from
funds then available to the Trustee, there shall be distributed on the
applicable Special Distribution Date, to the Person in whose name this
Certificate is registered at the close of business on the 15th day preceding the
Special Distribution Date, an amount in respect of such Special Payments on the
Notes, the receipt of which has been confirmed by the Trustee, equal to the
product of the percentage interest in the Trust evidenced by this Certificate
and an amount equal to the sum of such Special Payments so received. If a
Regular Distribution Date or Special Distribution Date is not a Business Day,
distribution shall be made on the next Business Day with the same force and
effect as if made on such Regular Distribution Date or Special Distribution Date
and interest shall accrue during the intervening period. The Trustee shall mail
notice of each Special Payment and the Special Distribution Date therefor to the
Certificateholder of this Certificate.

         Except as otherwise provided in the Agreement and notwithstanding the
above, the final distribution on this Certificate shall be made after notice
mailed by the Trustee of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Trustee specified in such notice.

         THE AGREEMENT AND THIS CERTIFICATE SHALL BE GOVERNED BY AND CONSTRUED
IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK (WITHOUT REGARD TO THE
PRINCIPLES OF CONFLICTS OF LAWS THEREOF (OTHER THAN SECTION 5-1401 OF THE NEW
YORK GENERAL OBLIGATIONS LAW)) AND THE OBLIGATIONS, RIGHTS AND REMEDIES OF THE
HOLDER OF THIS CERTIFICATE UNDER THE AGREEMENT SHALL BE DETERMINED IN ACCORDANCE
WITH SUCH LAWS.

         Reference is hereby made to the further provisions of this Certificate
set forth in the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

         Unless the certificate of authentication hereon has been executed by
the Trustee, by manual signature, this Certificate shall not be entitled to any
benefit under the Agreement or be valid or obligatory for any purpose.

<PAGE>   4

         IN WITNESS WHEREOF, the Trustee, on behalf of the Issuer and not in its
individual capacity, has caused this Certificate to be duly executed.

                                       UNITED AIRLINES 2000-2C PASS THROUGH
                                       TRUST

                                       By: STATE STREET BANK AND TRUST
                                           COMPANY OF CONNECTICUT,
                                           NATIONAL ASSOCIATION, not in its
                                           individual capacity but solely as
                                           Trustee

Dated: December 14, 2000               By: /s/ JOHN G. CORREIA
                                           Name: John G. Correia
                                           Title: Assistant Vice President

<PAGE>   5

                     TRUSTEE'S CERTIFICATE OF AUTHENTICATION

         This is one of the Certificates referred to in the within-mentioned
Trust Agreement.

State Street Bank and Trust Company of State Street Bank and Trust Company of
Connecticut, National Association, not in its Connecticut, National Association,
not in its individual capacity but solely as Trustee individual capacity but
solely as Trustee

By: /s/ JOHN G. CORREIA                               By: /s/ JOHN G. CORREIA
                                                        Authenticating Agent

                                                      By: /s/ JOHN G. CORREIA

<PAGE>   6

                            [REVERSE OF CERTIFICATE]

         The Certificates do not represent a direct obligation of, or an
obligation guaranteed by, or an interest in, the Company or the Trustee or any
of their Affiliates. The Certificates are limited in right or payment, all as
more specifically set forth on the face hereof and in the Agreement. All
payments or distributions made to Certificateholders under the Agreement shall
be made only from the Trust Property and only to the extent that the Trustee
shall have sufficient income or proceeds from the Trust Property to make such
payments in accordance with the terms of the Agreement. Each Certificateholder
of this Certificate, by its acceptance hereof, agrees that it shall look solely
to the income and proceeds from the Trust Property to the extent available for
distribution to such Certificateholder as provided in the Agreement. This
Certificate does not purport to summarize the Agreement and reference is made to
the Agreement for information with respect to the interests, rights, benefits,
obligations, proceeds and duties evidenced hereby. A copy of the Agreement may
be examined during normal business hours at the principal office of the Trustee,
and at such other places, if any, designated by the Trustee, by any
Certificateholder upon request.

         The Agreement permits, with certain exceptions therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Certificateholders under the Agreement at any time
by the Company and the Trustee with the consent of the Certificateholders
holding Certificates evidencing Fractional Cumulative Interests aggregating not
less than a majority in interest in the Trust. Any such consent by the
Certificateholder of this Certificate shall be conclusive and binding on such
Certificateholder and upon all future Certificateholders of this Certificate and
of any Certificate issued upon the transfer hereof or in exchange hereof or in
lieu hereof whether or not notation of such consent is made upon this
Certificate. The Agreement also permits the amendment thereof, in certain
limited circumstances, without the consent of the Certificateholders of any of
the Certificates.

         As provided in the Agreement and subject to certain limitations therein
set forth, the transfer of this Certificate is registrable in the Register upon
surrender of this Certificate for registration of transfer at the offices or
agencies maintained by the Trustee in its capacity as Registrar, or by any
successor Registrar, at its Corporate Trust Office, duly endorsed or accompanied
by a written instrument of transfer in form satisfactory to the Trustee and the
Registrar duly executed by the Certificateholder hereof or such
Certificateholder's attorney duly authorized in writing, and thereupon one or
more new Certificates of authorized denominations evidencing the same aggregate
Fractional Undivided Interest in the Trust shall be issued to the designated
transferee or transferees.

         The Certificates are issuable only as registered Certificates without
coupons in minimum denominations of $1,000 Fractional Undivided Interest and
integral multiples of $1,000 in excess thereof. As provided in the Agreement and
subject to certain limitations therein set forth, the Certificates are
exchangeable for new Certificates of authorized denominations evidencing the
same aggregate Fractional Undivided Interest in the Trust, as requested by the
Certificateholder surrendering the same.

<PAGE>   7

         No service charge shall be made for any such registration of transfer
or exchange, but the Trustee shall require payment by the Certificateholder of a
sum sufficient to cover any tax or governmental charge payable in connection
therewith.

         The Trustee, the Registrar, and any agent of the Trustee or the
Registrar may treat the person in whose name this Certificate is registered as
the owner hereof for all purposes, and neither the Trustee, the Registrar, nor
any such agent shall be affected by any notice to the contrary.

         The obligations and responsibilities created by the Agreement and the
Trust created thereby shall terminate upon the distribution to
Certificateholders of all amounts required to be distributed to them pursuant to
the Agreement and the disposition of all property held as part of the Trust
Property.<PAGE>   1
                                                                     EXHIBIT 4.1

     THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR ANY STATE SECURITIES LAWS. IT MAY NOT BE TRANSFERRED, ASSIGNED, SOLD
OR OFFERED FOR SALE EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER
SAID ACT AND ANY APPLICABLE STATE SECURITIES LAW OR AN OPINION OF COUNSEL, IN
FORM AND SUBSTANCE REASONABLY ACCEPTABLE TO THE COMPANY, THAT REGISTRATION IS
NOT REQUIRED BECAUSE OF AN APPLICABLE EXEMPTION FROM SUCH REGISTRATION
REQUIREMENTS.

         NO.  1                                                   $1,040,000

         DATED:  DECEMBER 8, 2000

                             VISUAL DATA CORPORATION

                  6% CONVERTIBLE DEBENTURE DUE DECEMBER 8, 2003

     THIS DEBENTURE ("DEBENTURE") is one of a duly authorized issue of
Debentures of VISUAL DATA CORPORATION (the "COMPANY"), a corporation duly
organized and existing under the laws of the State of Florida, designated as the
Company's 6% Convertible Debentures Due December 8, 2003, in an aggregate
principal amount of Two Million Forty Thousand U.S. Dollars (U.S. $2,040,000)
(the "DEBENTURES").

     FOR VALUE RECEIVED, the Company promises to pay to HALIFAX FUND, L.P. the
initial holder hereof, or its order (including successors-in-interest, the
"HOLDER"), the principal sum of ONE MILLION FORTY THOUSAND U.S. DOLLARS (U.S.
$1,040,000) on December 8, 2003 (the "MATURITY DATE") and to pay interest on the
principal sum outstanding under this Debenture ("OUTSTANDING PRINCIPAL AMOUNT"),
at the rate of 6% per annum, compounded semi-annually, payable in arrears on the
first day of March and September of each year and on the Maturity Date (each an
"INTEREST PAYMENT DATE"), with the first such payment due on March 1, 2001.
Interest shall accrue daily commencing on the date hereof and shall continue
until payment in full of all amounts due under this Debenture. The interest so
payable will be paid to the person in whose name this Debenture is registered on
the records of the Company regarding registration and transfers of the Debenture
(the "DEBENTURE REGISTER"). Capitalized terms used herein and not otherwise
defined shall have the meanings set forth in the Purchase Agreement dated as of
December 8, 2000 between the Company and the Holder (the "PURCHASE AGREEMENT")
or the Registration Rights Agreement dated as of December 8, 2000 between the
Company and the Holder (the "REGISTRATION RIGHTS AGREEMENT").

     The interest on this Debenture is payable, at the Company's option:

         (a) in such coin or currency of the United States which as of the time
of payment is legal tender for payment of public and private debts, at the
address last appearing on the Debenture Register of the Company as designated in
writing by the Holder hereof from time to time;

<PAGE>   2

         (b) by adding the amount thereof to the Outstanding Principal Amount
due under this Debenture ("PIK Interest"). For example, if the Outstanding
Principal Amount were $1,000 and the interest payment were $30, then the new
Outstanding Principal Amount after the Interest Payment Date would be $1,030;

         (c) subject, to the conditions set forth below, by paying the amount
in shares of Common Stock, with certificates for such shares (the "INTEREST
SHARES") to be delivered to the Holder on the Interest Payment Date. The number
of Interest Shares shall be determined by dividing the interest amount by 95% of
the average Market Price for Shares of Common Stock for the five (5) Trading
Days immediately preceding the Interest Payment Date ("INTEREST CONVERSION
PRICE"). The Company's ability to pay interest with Interest Shares is subject
to the following conditions:

             (i) No Event of Default, or event which, with the giving of notice
or the passage of time or both, would constitute an Event of Default shall have
occurred; and

             (ii) There shall be "EFFECTIVE REGISTRATION" (as defined in Section
3.1 of the Purchase Agreement) with respect to the Interest Shares and all the
share of Common Stock issuable upon conversation of this Debenture.

        In the event that the Interest Shares are not delivered to Holder within
3 Trading Days of the Interest Payment Date the interest shall be automatically
paid as PIK Interest pursuant to paragraph (b) above.

     Except as herein provided for interest, all amounts payable under this
Debenture shall be paid as provided in clause (a) above.

     The Company shall exercise its option hereunder by delivering an
irrevocable statement in the form of Exhibit 1 hereto ("PAYMENT STATEMENT")
delivered at least five (5) Trading Days prior to the applicable Interest
Payment Date and applicable for such Interest Payment Date only. If the Payment
Statement is not timely delivered to the Holder as provided herein, the payment
with respect to such Interest Payment Date shall be in PIK Interest. If the
Company selects cash interest in the Payment Statement and fails to deliver such
cash on or before the Interest Payment Date, the Holder shall have the right to
require the Company to pay PIK Interest in lieu thereof. Any PIK Interest when
so added to the Outstanding Principal Amount due under this Debenture shall, for
all purposes of this Debenture, be deemed to be part of the principal
indebtedness evidenced by this Debenture including, without limitation, for
purposes of determining interest payable hereunder after the applicable Interest
Payment Date for which such PIK Interest is paid and amounts convertible into
Common Shares hereunder after the applicable Interest Payment Date for which
such PIK Interest is paid.

     The Company will pay any principal due and all accrued and unpaid interest
due upon this Debenture to the person that is the Holder of this Debenture on
the records of the Company as of the applicable Interest Payment Date and
addressed to such Holder at the last address appearing on the Debenture
Register.

                                       2

<PAGE>   3

     The Outstanding Principal Amount and interest due hereunder shall bear
interest, from and after the day following the occurrence and during the
continuance of an Event of Default hereunder, at the per annum rate equal to the
lower of the Citibank Prime Rate per annum plus six (6%) percent or the highest
rate permitted by law. The Holder shall have the option to receive such interest
as cash interest or PIK Interest and shall exercise its option by delivering to
the Company a statement in a form substantially similar to the Payment Statement
which shall be effective until the Holder delivers an additional statement to
the contrary. If the Holder elects to receive the interest in cash, it shall be
payable on demand.

     Subject to applicable law, any interest otherwise payable that is not paid
for any applicable period because it would exceed the highest rate permitted by
law shall become payable whenever the payment thereof, together with other
interest due for any such subsequent period, would not exceed such highest legal
rate.

     The Holder of this Debenture is entitled to certain rights and remedies
pursuant to the Purchase Agreement and Registration Rights Agreement, including
without limitation provisions requiring mandatory redemption of the Debenture.
This Debenture does not provide voting rights to the Holder.

     This Debenture is subject to the following additional provisions:

     1. Exchange. The Debentures are exchangeable for an equal aggregate
principal amount of Debentures of different denominations, as requested by the
Holder surrendering the same. No service charge will be made for such
registration or transfer or exchange.

     2. Transfers. This Debenture may be transferred or exchanged in the United
States only in compliance with the Securities Act of 1933, as amended (the
"ACT") and applicable state securities laws, or applicable exemptions therefrom.
Prior to due presentment for transfer of this Debenture, the Company may treat
the person in whose name this Debenture is duly registered on the Company's
Debenture Register as the owner hereof for the purpose of receiving payment as
herein provided, whether or not this Debenture is overdue.

     3. Definitions. For purposes hereof the following definitions shall apply:

        "ACT" shall have the meaning set forth in Section 2.

        "ADJUSTMENT DATE" shall have the meaning set forth in Section 6(b).

        "AFFECTED CONVERSION PRICE" shall have the meaning set forth in
Section 6(a).

        "CHANGE IN CONTROL CONSIDERATION" shall have the meaning set forth in
Section 4 hereof.

                                       3
<PAGE>   4

        "CHANGE IN CONTROL CONVERSION PRICE" shall have the meaning set forth
in Section 4 hereof.

        "CHANGE IN CONTROL TRANSACTION" shall mean (i) any consolidation or
merger of the Company with or into any other corporation or other entity or
person (whether or not the Company is the surviving corporation), or any other
corporate reorganization or transaction or series of related transactions in
which in excess of 50% of the Company's voting power is transferred through a
merger, consolidation, tender offer or similar transaction; or (ii) any person
(as defined in Section 13(d) of the Securities Exchange Act of 1934, as amended
(the "EXCHANGE ACT")), together with its affiliates and associates (as such
terms are defined in Rule 405 under the Act), beneficially owns or is deemed to
beneficially own (as described in Rule 13d-3 under the Exchange Act without
regard to the 60-day exercise period) in excess of 50% of the Company's voting
power; (iii) there is a replacement of more than one-half of the members of the
Company's Board of Directors which is not approved by those individuals who are
members of the Company's Board of Directors on the date thereof; or (iv) in one
or a series of related transactions there is a sale or transfer of all or
substantially all of the assets of the Company, determined on a consolidated
basis.

        "CLOSING DATE" shall mean the date of the original issuance of this
Debenture.

        "COMMON STOCK" shall mean the common stock, par value $0.0001, of the
Company.

        "COMPANY" shall have the meaning set forth in the Preamble.

        "CONVERSION NOTICE" shall have the meaning set forth in Section 5(d).

        "CONVERTIBLE SECURITIES " shall have the meaning set forth in
Section 6(b).

        "CONVERSION PRICE" shall have the meaning set forth in Section 5(c).

        "CONVERSION RATE" shall have the meaning set forth in Section 5(b).

        "DEBENTURE" shall have the meaning set forth in the Preamble.

        "DEBENTURES" shall have the meaning set forth in the Preamble.

        "DEBENTURE REGISTER" shall have the meaning set forth in the Preamble.

        "DTC" shall have the meaning set forth in Section 5(e).

        "DWAC" shall have the meaning set forth in Section 5(e).

        "FAST" shall have the meaning set forth in Section 5(e).

                                       4
<PAGE>   5

        "HOLDER CONVERSION DATE" shall have the meaning set forth in
Section 5(d).

        "INTEREST PAYMENT DATE" shall have the meaning set forth in the
Preamble.

        "MATURITY DATE" shall have the meaning set forth in the Preamble.

        "MARKET PRICE FOR SHARES OF COMMON STOCK" shall mean the price
of one share of Common Stock determined as follows:

             (i) If the Common Stock is approved for trading on the NASDAQ
National Market System or the Nasdaq Small-Cap Market, the last reported "bid"
price thereon on the date of valuation;

             (ii) If (i) does not apply and the Common Stock is listed on NYSE
or the American Stock Exchange, the closing bid price on such exchange on the
date of valuation;

             (iii) If neither (i) nor (ii) apply but the Common Stock is quoted
in the over-the-counter market, another recognized exchange, on the pink sheets
or bulletin board, (A) the last sales price on the date of valuation or, if
there is no such sales price, (B) the mean between the last reported "bid" and
"asked" prices thereof on the date of valuation; and

             (iv) If neither clause (i), (ii) or (iii) above applies, the market
value as determined by a nationally recognized investment banking firm or other
nationally recognized financial advisor retained by the Company for such
purpose, taking into consideration, among other factors, the earnings history,
book value and prospects for the Company, and the prices at which shares of
Common Stock recently have been traded. Such determination shall be conclusive
and binding on all persons.

        "NYSE" shall mean the New York Stock Exchange.

        "OUTSTANDING PRINCIPAL AMOUNT" shall have the meaning set forth in the
Preamble.

        "PAYMENT STATEMENT" shall have the meaning set forth in the Preamble.

        "PIK INTEREST" shall have the meaning set forth in the Preamble.

        "PUBLIC ANNOUNCEMENT" shall mean any public filing with the
Securities and Exchange Commission, any press release by either the Company or a
third party or any other public statement, that announces a proposed transaction
which, if consummated, would constitute a Change in Control Transaction.

        "PURCHASE AGREEMENT" shall have the meaning set forth in the Preamble.

        "REDEMPTION PRICE" shall have the meaning set forth in Section 4(a).

                                       5
<PAGE>   6

        "REGISTRATION STATEMENT" shall have the meaning set forth in the
Registration Rights Agreement.

        "REGISTRATION RIGHTS AGREEMENT" shall have the meaning set forth in the
Preamble.

        "RESTRICTED OWNERSHIP PERCENTAGE" shall have the meaning set forth in
Section 11.

        "TRADING DAY" shall mean a day on which the Common Stock is
traded on the NASDAQ National Market or principal exchange on which the Common
Stock has been listed (or any similar organization or agency succeeding such
market or exchange's functions of reporting prices).

     4. Change in Control, Etc.

        (a) If at any time there occurs any Change in Control Transaction,
Holder shall be entitled, at its sole option, to have the Company redeem this
Debenture in whole or in part at a Redemption Price equal to 115% of the
Outstanding Principal Amount of this Debenture plus all accrued but unpaid
interest and delay payments on this Debenture (the "REDEMPTION PRICE"). Such
Holder shall be entitled to make such election at any time after a Public
Announcement of a pending and up to 10 days after the effective date of the
Change in Control Transaction.

        (b) If at any time there occurs a Public Announcement of a pending
Change in Control Transaction in which the public shareholders of the Company
are to receive consideration, a portion of which is capital stock or any
security convertible into capital stock of another entity in exchange for shares
of Common Stock ("CHANGE IN CONTROL CONSIDERATION"), then prompt provision shall
be made in a manner reasonably acceptable to the Holders so that each Holder
shall have the right (in addition to its other rights under this Debenture):

            (i) following the closing of the transaction covered by such Public
Announcement, to convert its Debentures into the Change in Control Consideration
that such Holder would have been or would be entitled to receive had it
converted all of its Debentures into Common Stock (notwithstanding any
restrictions imposed upon the Holder pursuant to this Debenture or the Purchase
Agreement in its ability to do so) immediately prior to the Change in Control
Transaction at the Change in Control Conversion Price (as defined below), and
acquired the Change in Control Consideration as a shareholder of the Company; or

            (ii) following such Public Announcement, convert its Debentures into
Common Stock at the Change in Control Conversion Price (as defined below).

            The "CHANGE IN CONTROL CONVERSION PRICE" shall mean a price, subject
to adjustments in the same manner as adjustments to the Conversion Price, equal
to the lesser of: (i) the then existing Conversion Price (as defined in Section
5(c) below);

                                       6
<PAGE>   7

(ii) 100% of the lowest Market Price for Shares of Common Stock for any of the
four Trading Days immediately preceding the Public Announcement of the Change in
Control Transaction; and (iii) 85% of the lowest Market Price for Shares of
Common Stock on the three Trading Days immediately following the Public
Announcement. The Market Price for Shares of Common Stock shall be appropriately
adjusted for stock splits, reverse splits, stock dividends and other dilutive
events applicable to all stockholders, including those events occurring in
connection with the Change in Control Transaction, that occur during the Trading
Days referred to above.

     5. Conversion at the Option of the Holder. The Holder of this Debenture
shall have the following conversion rights:

        (a) Holder's Right to Convert. The Holder shall have the right at any
time and from time to time prior to payment in full of this Debenture, at the
Holder's option, to convert any or all of this Debenture for such number of
fully paid, validly issued and nonassessable shares of Common Stock, as is
determined pursuant to this Section 5.

        (b) Conversion Rate. The Outstanding Principal Amount of this Debenture
that is converted into shares of Common Stock at the option of the Holder shall
be convertible into the number of shares of Common Stock which results from
application of the following formula:

                                      P + I

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

                                Conversion Price

    P=   Outstanding Principal Amount of this Debenture submitted for
         conversion as of the Holder Conversion Date

    I=   accrued but unpaid interest (not previously added to principal)
         on P as of the Holder Conversion Date

            The number of shares of Common Stock into which each $1,000
principal amount of this Debenture hereto may be converted pursuant to this
paragraph hereof is hereafter referred to as the "CONVERSION RATE."

        (c) Conversion Price. (i) Subject to the adjustments set forth below,
the "CONVERSION PRICE" shall be equal to the lesser of:

            (A) $2.13 (the "MAXIMUM CONVERSION PRICE"); and

            (B) 90% of the average of the three lowest Market Prices for Shares
                of Common Stock for the 20 Trading Days immediately  prior to
                the date of the Conversion Notice (as defined below) (the
                "VARIABLE CONVERSION PRICE").

                                       7
<PAGE>   8

            Notwithstanding the foregoing, the Conversion Price may not be less
than the Floor Price (as defined below), except where the Conversion Price is
adjusted pursuant to Section 6(b) below, in which event the Floor Price shall
cease to apply.

            (i) As used herein, the "FLOOR PRICE" shall be equal to $0.90;
provided that on December 8, 2001, the Floor Price shall be reset to 50% of the
Variable Conversion Price on such date, if such reset would result in a lower
Floor Price. In the event that the Conversion Price is adjusted pursuant to
Section 6(b) below, the Floor Price shall cease to apply.

            (ii) In addition, the Maximum Conversion Price, the Variable
Conversion Price and the Floor Price are subject to adjustment pursuant to
Section 2(b)(i) of the Registration Rights Agreement.

        (d) Mechanics of Conversion. In order to convert this Debenture (in
whole or in part) into full shares of Common Stock, the Holder (i) shall give
written notice in the form of Exhibit 2 hereto (the "CONVERSION NOTICE") by
facsimile to the Company at such office that the Holder elects to convert the
principal amount (plus accrued but unpaid interest and Delay Payments (as
defined in the Registration Rights Agreement) specified therein, which such
notice and election shall be irrevocable by the Holder unless the Common Stock
shall not have been delivered within five Trading Days of the date the
Conversion Notice is delivered to the Company, and (ii) if the entire
Outstanding Principal Amount is being converted, as soon as practicable after
such notice, shall surrender this Debenture, duly endorsed, by either overnight
courier or 2-day courier, to the principal office of the Company; provided,
however, that the Company shall not be obligated to issue certificates
evidencing the shares of the Common Stock issuable upon such conversion (where
the entire Outstanding Principal Amount is being converted) unless either the
Debenture evidencing the principal amount is delivered to the Company as
provided above, or the Holder notifies the Company that such Debenture(s) have
been lost, stolen or destroyed and promptly executes an agreement reasonably
satisfactory to the Company to indemnify the Company from any loss incurred by
it in connection with such lost, stolen or destroyed Debentures.

            The Holder shall not be required to physically surrender this
Debenture to the Company unless the full Outstanding Principal Amount
represented by this Debenture is being converted. The Holder and the Company
shall maintain records showing the Outstanding Principal Amount so converted and
the dates of such conversions or shall use such other method, reasonably
satisfactory to the Holder and the Company, so as not to require physical
surrender of this Debenture upon each such conversion. In the event of any
dispute or discrepancy, such records of the Company shall be controlling and
determinative in the absence of manifest error. Notwithstanding the foregoing,
if this Debenture is converted as aforesaid, the Holder may not transfer this
Debenture unless the Holder first physically surrenders this Debenture to the
Company, whereupon the Company will forthwith issue and deliver upon the order
of the Holder a new Debenture of like tenor, registered as the Holder may
request, representing in the aggregate the remaining Outstanding Principal
Amount represented by this Debenture. The Holder and any assignee, by acceptance
of this Debenture or a new Debenture,

                                       8
<PAGE>   9

acknowledge and agree that, by reason of the provisions of this paragraph,
following conversion of any portion of this Debenture, the Outstanding Principal
Amount represented by this Debenture may be less than the Outstanding Principal
Amount and the accrued interest set forth on the face hereof.

            The Company shall issue and deliver within five Trading Days of the
delivery to the Company of such Conversion Notice, to such Holder of
Debenture(s) at the address of the Holder, or to its designee, a certificate or
certificates for the number of shares of Common Stock to which the Holder shall
be entitled as aforesaid, together with a calculation of the Conversion Rate
and, if the Debenture has been surrendered and is being converted in part only,
a Debenture or Debentures for the principal amount of Debentures not submitted
for conversion. The date on which the Conversion Notice is given (the "HOLDER
CONVERSION DATE") shall be deemed to be the date the Company received by
facsimile the Conversion Notice provided that if not received by 5 p.m. on such
date, the Holder Conversion Date shall be deemed to be the next Trading Day, and
the person or persons entitled to receive the shares of Common Stock issuable
upon such conversion shall be treated for all purposes as the record holder or
holders of such shares of Common Stock on such date. In the event that such
Holder or its designee has not received such certificate or certificates within
ten (10) calendar days of the Company's receipt of the Conversion Notice, the
Holder may, in addition to any other rights or remedies it may have, revoke its
Conversion Notice.

        (e) In lieu of delivering physical certificates representing the shares
of Common Stock issuable upon conversion of this Debentures, provided the
Company's transfer agent is participating in the Depository Trust Company
("DTC") Fast Automated Securities Transfer ("FAST") program, upon request of the
Holder, the Company shall use its best efforts to cause its transfer agent to
electronically transmit the shares of Common Stock issuable upon conversion of
this Debenture to the Holder, by crediting the account of Holder's prime broker
with DTC through its Deposit Withdrawal Agent Commission ("DWAC") system. The
time periods for delivery described above shall apply to the electronic
transmittals through the DWAC system. The parties agree to coordinate with DTC
to accomplish this objective. The conversions pursuant to Sections 5 shall be
deemed to have been made immediately prior to the close of business on the
Holder Conversion Date. The person or persons entitled to receive the share of
Common Stock issuable upon such conversion shall be treated for all purposes as
the record holder or holders of such shares at the close of business on the
Holder Conversion Date.

                                       9
<PAGE>   10

     6. Stock Splits; Dividends; Adjustments; Reorganizations.

        (a) If the Company, at any time while the Debentures are outstanding,
shall (i) pay a stock dividend or otherwise make a distribution or distributions
on any equity securities (including investments or securities convertible into
or exchangeable for such equity securities) in shares of Common Stock, (ii)
subdivide the outstanding shares of Common Stock into a larger number of shares,
(iii) combine outstanding shares of Common Stock into a smaller number of
shares, then each Affected Conversion Price (as defined below) shall be
multiplied by a fraction of which the numerator shall be the number of shares of
Common Stock outstanding before such event and of which the denominator shall be
the number of shares of Common Stock outstanding after such event. Any
adjustment made pursuant to this Section 6(a) shall become effective immediately
after the record date for the determination of shareholders entitled to receive
such dividend or distribution and shall become effective immediately after the
effective date in the case of an issuance, a subdivision or a combination.

        As used herein, the Affected Conversion Prices (each an "AFFECTED
CONVERSION PRICE") shall refer to: (1) the Maximum Conversion Price; (2) the
Floor Price and (3) each Market Price for Shares of Common Stock occurring on
any Trading Day included in the period used to determine the Variable Conversion
Price, which Trading Day occurred before the record date in the case of events
referred to in clause (i) above of this Section 6(a) and the effective date in
the case of the events referred to in clauses (ii) and (iii) above of this
Section 6(a).

        (b) In the event that the Company issues or sells any Common Stock or
securities which are convertible into or exchangeable for its Common Stock, or
any warrants or other rights to subscribe for or to purchase or any options for
the purchase of its Common Stock ("CONVERTIBLE SECURITIES") at a per share of
Common Stock selling price ("PER SHARE SELLING PRICE") which is less than the
Floor Price on the Trading Day next preceding such issue or sale or, in the case
of issuances to holders of its Common Stock, the date fixed for the
determination of stockholders entitled to receive such warrants, rights or
options (the "ADJUSTMENT DATE"), then the Conversion Price per share shall be
adjusted downward to equal such lower Per Share Selling Price effective
concurrently with such issue or sale.

        In the event that the Company issues or sells any Common Stock or any
Convertible Securities at a Per Share Selling Price which is greater than the
Floor Price but less than the Conversion Price on the Adjustment Date, then the
Conversion Price in effect immediately prior to such issue or sale shall be
reduced effective concurrently with such issue or sale to an amount determined
by multiplying the Conversion Price then in effect by a fraction, (x) the
numerator of which shall be the sum of (1) the number of shares of Common Stock
outstanding immediately prior to such issue or sale, plus (2) the number of
shares of Common Stock which the aggregate consideration received by the Company
for such additional shares would purchase at such Conversion Price then in
effect; and (y) the denominator of which shall be the number of shares of Common
Stock of the Company outstanding immediately after such issue or sale.

                                       10
<PAGE>   11

        Notwithstanding the foregoing, this provision shall not apply to shares
or options issued or which may be issued pursuant to (i) the Company's current
or future employee, director or bona fide consultant options; (ii) shares issued
upon exercise of options, warrants or rights outstanding on the date of the
Purchase Agreement; provided that during the first year following the Closing
Date (as defined in the Purchase Agreement) the total number of such shares and
options which are vested and to be issued from the date hereof shall not exceed
1.5 million; (iii) strategic corporate alliances not undertaken principally for
financing purposes; (iv) arrangements with the Holder; (v) acquisitions of other
entities by the Company; and (vi) warrants issued on customary terms in
traditional bank financings.

        For the purposes of the foregoing adjustment, in the case of the
issuance of any Convertible Securities, the maximum number of shares of Common
Stock issuable upon exercise, exchange or conversion of such Convertible
Securities shall be deemed to be issued and outstanding based upon a Per Share
Selling Price equal to the lowest price at which Common Stock can be acquired
pursuant to the Convertible Securities, provided that no further adjustment
shall be made upon the actual issuance of Common Stock upon exercise, exchange
or conversion of such Convertible Securities.

        (c) If the Company, at any time while the Debentures are outstanding,
shall distribute to all holders of shares of Common Stock evidences of its
indebtedness or assets or rights or warrants to subscribe for or purchase any
security (excluding those referred to in Section 6(b) above), then the prices
referred to in (3) of the definition of the Affected Conversion Prices set forth
in Section 6(a) above shall be reduced to equal the relevant Affected Conversion
Price multiplied by a fraction (i) the numerator of which is equal to (A) the
Market Price for Shares of Common Stock on the record date for the distribution
minus (B) the price allocable to one share of Common Stock of the value (as
jointly determined in good faith by the board of directors of the Company and
the Holder) of any and all such evidences of indebtedness, shares of capital
stock, other securities or property, so distributed and (ii) the denominator of
which is equal to the Market Price for Shares of Common Stock on the record date
for the distribution.

        (d) In the event that at any time or from time to time after the Closing
Date, the Common Stock issuable upon the conversion of the Debentures is changed
into the same or a different number of shares of any class or classes of stock,
whether by merger, consolidation, recapitalization, reclassification or
otherwise (other than a subdivision or combination of shares or stock dividend
or reorganization provided for elsewhere in this Section 6), then and as a
condition to each such event provision shall be made in a manner reasonably
acceptable to the Holders of Debentures so that each Holder of Debentures shall
have the right thereafter to convert such Debenture into the kind of stock
receivable upon such recapitalization, reclassification or other change by
holders of shares of Common Stock, all subject to further adjustment as provided
herein. In such event, the formulae set forth herein for conversion and
redemption shall be equitably adjusted to reflect such change in number of
shares or, if shares of a new class of stock are issued, to reflect the market
price of the class or classes of stock (applying the same factors used in
determining the Conversion Price) issued in connection with the above described
transaction.

                                       11
<PAGE>   12

        (e) Whenever any element of the Conversion Price is adjusted pursuant
to this Section 6, the Company shall promptly mail to each Holder of the
Debentures, a notice setting forth the Conversion Price after such adjustment
and setting forth a brief statement of the facts requiring such adjustment.

        (f) In the event of any taking by the Company of a record date of the
holders of any class of securities for the purpose of determining the holders
thereof who are entitled to receive any dividend or other distribution, any
security or right convertible or exchangeable into or entitling the holder
thereof to receive additional shares of Common Stock, or any right to subscribe
for, purchase or otherwise acquire any shares of stock of any class or any other
securities or property, or to receive any other right, the Company shall deliver
to each Holder of Debentures at least 10 days prior to the date specified
therein, a notice specifying the date on which any such record is to be taken
for the purpose of such dividend, distribution, security or right and the amount
and character of such dividend, distribution, security or right.

        (g) If the Company, at any time while the Debentures are outstanding,
shall distribute to all holders of Shares of Common Stock evidences of its
indebtedness or assets or rights or warrants to subscribe for or purchase any
security (excluding those referred to in Section 6(c) above) then the Holder
shall participate in such distribution on a pro rata basis with the holders of
shares of Common Stock entitled to receive such dividend, distribution,
issuance, subdivision or combination as if the Holder held that number of shares
of Common Stock that the Holder would have been entitled to receive hereunder
upon conversion of the Debenture (without regard to Section 11) immediately
prior to the record date fixed for determination of shareholders entitled to
receive such dividend, at the Conversion Price then in existence.

        (h) In addition the Conversion Price is subject to adjustment as
provided in Section 2(b)(i) of the Registration Rights Agreement.

     7. FRACTIONAL SHARES. No fractional shares of Common Stock or scrip
representing fractional shares of Common Stock shall be issuable hereunder. The
number of shares of Common Stock that are issuable upon any conversion shall be
rounded up to the nearest whole share.

     8. Reservation of Stock Issuable Upon Conversion.

        (a) Reservation Requirement. The Company covenants that it will at all
times reserve and keep available out of its authorized and unissued Common Stock
solely for the purpose of issuance upon conversion of the Debentures as herein
provided, free from preemptive rights or any other present or contingent
purchase rights of persons other than the Holders of the Debentures, 200% of the
maximum number of shares of Common Stock as shall be issuable (taking into
account the adjustments and restrictions of Sections 5 and 6 hereof) upon the
conversion of all of the Debentures pursuant hereto. The Company covenants that
all shares of Common Stock that shall be so issuable shall upon issuance, be
duly and validly authorized, issued and fully paid and nonassessable. Without in
any way limiting the foregoing, so long as any Debentures remain outstanding the
Company agrees to reserve and at all times keep available solely for purposes of

                                       12
<PAGE>   13

conversion of Debentures such number of authorized but unissued shares of Common
Stock that is set forth in the Purchase Agreement.

        (b) Deficiency. If the Company does not have a sufficient number of
shares of Common Stock available to satisfy the Company's obligations to a
Holder of Debentures upon receipt of a Conversion Notice or is otherwise unable
to issue such shares of Common Stock in accordance with the terms of this
Agreement such Holder shall be entitled to the rights and remedies set forth in
the Registration Rights Agreement.

     9.  No Reissuance of the Debenture. No Debentures acquired by the Company
by reason of redemption, purchase, exchange or otherwise shall be reissued, and
all such Debentures shall be retired.

     10. No Impairment. The Company shall not knowingly and intentionally take
any action which would impair the rights and privileges of the Debentures set
forth herein or the Holders thereof.

     11. Limitations on Holder's Right to Convert.

         (a) Notwithstanding anything to the contrary contained herein, the
number of shares of Common Stock that may be acquired by the Holder upon
conversion of this Debenture pursuant to the terms hereof shall not exceed a
number that, when added to the total number of shares of Common Stock deemed
beneficially owned by such Holder (other than by virtue of the ownership of
securities or rights to acquire securities that have limitations on the holder's
right to convert, exercise or purchase similar to the limitation set forth
herein), together with all shares of Common Stock deemed beneficially owned
(other than by virtue of the ownership of securities or rights to acquire
securities that have limitations on the right to convert, exercise or purchase
similar to the limitation set forth herein) by the Holder's "affiliates" (as
defined in Rule 144 of the Act) ("AGGREGATION PARTIES") that would be aggregated
for purposes of determining whether a group under Section 13(d) of the Exchange
Act, exists, would exceed 9.99% of the total issued and outstanding shares of
the Common Stock (the "RESTRICTED OWNERSHIP PERCENTAGE"). Each Holder shall have
the right (i) at any time and from time to time to reduce its Restricted
Ownership Percentage immediately upon notice to the Company and (ii) (subject to
waiver) at any time and from time to time, to increase its Restricted Ownership
Percentage immediately in the event of the announcement as pending or planned,
of a Change of Control Transaction.

         (b) The Holder covenants at all times on each day (each such day being
referred to as a "COVENANT DAY") as follows: During the balance of such Covenant
Day and the succeeding sixty-one (61) days (the balance of such Covenant Day and
the succeeding 61 days being referred to as the "COVENANT PERIOD") such Holder
will not acquire shares of Common Stock pursuant to any right existing at the
commencement of the Covenant Period to the extent the number of shares so
acquired by such Holder and its Aggregation Parties (ignoring all dispositions)
would exceed:

                                       13
<PAGE>   14
             (x) the Restricted Ownership Percentage of the total number of
             shares of Common Stock outstanding at the commencement of the
             Covenant Period,

             minus

             (y) the number of shares of Common Stock owned by such Holder and
             its Aggregation Parties at the commencement of the Covenant Period.

         A new and independent covenant will be deemed to be given by the Holder
as of each moment of each Covenant Day. No covenant will terminate, diminish or
modify any other covenant. The Holder agrees to comply with each such covenant.
This Section 11 controls in the case of any conflict with any other provision of
any other agreement to which the Company and the Holder may be parties.

         (c) The Company's obligation to issue shares of Common Stock which
would exceed such limits referred to in this Section 11 shall be suspended to
the extent necessary until such time, if any, as shares of Common Stock may be
issued in compliance with such restrictions.

     12. Company Redemption Right.

         (a) Following the date hereof, in the event that the Market Price for
Shares of Common Stock shall be less than $1.50 (as may be equitably adjusted
for subsequent stock splits, reverse splits, consolidations and stock dividends)
for 20 consecutive Trading Days (the "REDEMPTION TRIGGERING EVENT"), then the
Company shall have the right within 20 Trading Days of the Redemption Triggering
Event to deliver written notice (the "Redemption Notice") to the Holder, to
redeem all or a portion of this Debenture at 115% of the Outstanding Principal
Amount plus all accrued but unpaid interest and all Delay Payments thereon (the
"Redemption Price"), subject to the conditions set forth below. The foregoing
redemption right (the "REDEMPTION RIGHT") shall, if exercised, be irrevocable
and may be exercised no more than twice and if exercised, may not be exercised
again until 3 months after the first Redemption Closing Date (as defined below).

         (b) The Redemption Notice shall set forth a date (the "REDEMPTION
CLOSING DATE") for the redemption of the Debenture, which shall be no less than
5 Trading Days nor more than 20 Trading Days from the date of the Redemption
Notice. Subject to the book entry provisions of Section 5(d) above, the Holder
shall promptly upon receipt of such notice, surrender the Debenture to be
redeemed duly endorsed, at the office of the Company. On the Redemption Closing
Date the Company shall transmit (1) the Redemption Price; and (2) if the book
entry provision of Section 5(d) are not being used, any new Debentures
representing the amount of Debentures not redeemed, to the Holder by not later
than 2 Trading Days after the Redemption Closing Date. In the event that the
Redemption Price is not paid on the Redemption Closing Date, then (x) the Holder
shall have the immediate right to request redemption of this Debenture pursuant

                                       14
<PAGE>   15

to Section 2(b)(iv) of the Registration Rights Agreement and (y) the Company
shall lose any further right to redeem Debentures pursuant to this Section.

         (c) The Company's right to redeem this Debenture pursuant to the
redemption right, is subject to the following conditions:

             (i)  there shall be no existing Event of Default or event which,
                  with the giving of notice or the passage of time or both would
                  constitute an Event of Default under any Debentures;

             (ii) there shall be Effective Registration (as defined in the
                  Purchase Agreement) with respect to the shares issuable upon
                  conversion of or as interest on, all of the Debentures.

         (d) Holder shall have the right to convert this Debenture at all times
until the Redemption Closing Date.

     13. Obligations Absolute. No provision of this Debenture, the Purchase
Agreement or the Registration Rights Agreement shall alter or impair the
obligation of the Company, which is absolute and unconditional, to pay the
principal of, and interest and delay payments on, this Debenture or to issue
shares of Common Stock in response to a Conversion Notice at the time, place and
rate, and in the manner, herein prescribed, except that if the Company disputes
the Holder's calculation of the number of shares to be issued upon a conversion,
the Company shall deliver to Holder the number of shares not in dispute and the
parties shall have the calculation dispute resolved by a third party mutually
acceptable to them.

     14. Waivers of Demand, Etc. The Company hereby expressly and irrevocably
waives demand and presentment for payment, notice of nonpayment, protest, notice
of protest, notice of dishonor, notice of acceleration or intent to accelerate,
bringing of suit and diligence in taking any action to collect amounts called
for hereunder and will be directly and primarily liable for the payment of all
sums owing and to be owing hereon, regardless of and without any notice,
diligence, act or omission as or with respect to the collection of any amount
called for hereunder.

     15. Replacement Debenture. In the event that any Holder notifies the
Company that its Debenture(s) have been lost, stolen or destroyed, replacement
Debenture(s) identical in all respects to the original Debenture(s) (except for
registration number and Outstanding Principal Amount, if different than that
shown on the original Debenture(s)), shall be issued to the Holder, provided
that the Holder executes and delivers to the Company an agreement reasonably
satisfactory to the Company to indemnify the Company from any loss incurred by
it in connection with such Debenture.

     16. Payment of Expenses; Issue Taxes. The Company agrees to pay all debts
and expenses, including reasonable attorneys' fees, which may be incurred by the
Holder in enforcing the provisions of this Debenture and/or collecting any
amount due under this Debenture, the Purchase Agreement, any Warrant or the
Registration Rights Agreement.

                                       15
<PAGE>   16

The Company shall pay any and all issue and other taxes (excluding any income,
franchise or similar taxes) that maybe payable in respect of any issue or
delivery of shares of Common Stock on conversion of any Debenture pursuant
hereto.

     17. Defaults. If one or more of the following described "EVENTS OF DEFAULT"
shall occur with respect to any of the Debentures:

          (a)  the Company shall default in the payment of (i) interest on this
               Debenture or any other Debenture issued pursuant to the Purchase
               Agreement (subject to the Company's option to pay PIK Interest),
               and such default shall continue for five (5) Trading Days after
               the due date thereof, or (ii) the principal of this Debenture or
               any other Debenture issued pursuant to the Purchase Agreement; or

          (b)  any of the representations or warranties made by the Company in
               any of the Debentures, in the Purchase Agreement, the
               Registration Rights Agreement, any Warrant or in any certificate
               or financial or other statements heretofore or hereafter
               furnished by or on behalf of the Company in connection with the
               execution and delivery of this Debenture or such other documents
               shall be false or misleading at the time made; or

          (c)  the Company shall fail to materially perform or observe any
               covenant or agreement in the Purchase Agreement, any Warrant or
               the Registration Rights Agreement, or any other covenant, term,
               provision, condition, agreement or obligation of the Company
               under any of the Debentures and such failure shall continue
               uncured for a period of fifteen (15) days after notice of such
               failure; or

          (d)  the Company shall (1) become insolvent; (2) admit in writing its
               inability to pay its debts generally as they mature; (3) make an
               assignment for the benefit of creditors or commence proceedings
               for its dissolution; or (4) apply for or consent to the
               appointment of a trustee, liquidator or receiver for it or for a
               substantial part of its property or business; or

          (e)  a trustee, liquidator or receiver shall be appointed for the
               Company or for a substantial part of its property or business
               without its consent and shall not be discharged within forty-five
               (45) days after such appointment; or

          (f)  any governmental agency or any court of competent jurisdiction at
               the instance of any governmental agency shall assume custody or
               control of the whole or any substantial portion of the properties
               or assets of the Company and shall not be dismissed within
               forty-five (45) days thereafter; or

                                       16
<PAGE>   17

          (g)  the Company shall, in one or a series of transactions, sell or
               otherwise transfer all or substantially all of its assets; or

          (h)  bankruptcy, reorganization, insolvency or liquidation proceedings
               or other proceedings, or relief under any bankruptcy law or any
               law for the relief of debt shall be instituted by or against the
               Company and, if instituted against the Company shall not be
               dismissed within forty-five (45) days after such institution, or
               the Company shall by any action or answer approve of, consent to,
               or acquiesce in any such proceedings or admit to any material
               allegations of, or default in answering a petition filed in any
               such proceeding; or

          (i)  the Company shall be in default of any other of its indebtedness
               exceeding $1,000,000, or any other event shall have occurred such
               that as a result thereof the holders thereof shall have
               accelerated or shall have the right (upon the giving of notice,
               the passage of time, or both) to accelerate such indebtedness; or

          (j)  any money judgment, writ or warrant of attachment, or similar
               process in excess of Five Hundred Thousand Dollars (US$500,000)
               in the aggregate shall be entered or filed against the Company or
               any of its properties or other assets and shall remain unpaid,
               unvacated, unbonded and unstayed for a period of forty-five (45)
               days; or

          (k)  a "going private" transaction under Rule 13e-3 promulgated
               pursuant to the Exchange Act shall have been announced; or

          (l)  a tender offer by the Company under Rule 13e-4 promulgated
               pursuant to the Exchange Act shall have been announced;

     then, or at any time thereafter, in the case of Events of Default arising
from the events described in paragraphs (a), (b), (c), (g) (i), (j), (k) and
(l), unless such Event of Default shall have been waived in writing by the
Holder (which waiver shall not be deemed to be a waiver of any subsequent
default) at the option of the Holder and in the Holder's sole discretion, the
Holder may declare the Debenture immediately due and payable and concurrently
demand payment thereof, and the Holder may immediately, and without expiration
of any period of grace, enforce any and all of the Holder's rights and remedies
provided herein or any other rights or remedies afforded by law. In the event of
Events of Default arising from the events described in paragraphs (d), (e), (f)
or (h) above, this Debenture shall become immediately due and payable without
further action or notice. In the event that the Debenture is due and payable
pursuant to this provision, the Debenture shall be redeemed at the Premium
Redemption Price (as defined in the Registration Rights Agreement).

     18. Savings Clause. In case any provision of this Debenture is held by a
court of competent jurisdiction to be excessive in scope or otherwise invalid or
unenforceable,

                                       17
<PAGE>   18

such provision shall be adjusted rather than voided, if possible, so that it is
enforceable to the maximum extent possible, and the validity and enforceability
of the remaining provisions of this Debenture will not in any way be affected or
impaired thereby, and such provision shall remain effective in all other
jurisdictions.

     19. Entire Agreement. This Debenture and the agreements referred to in this
Debenture constitute the full and entire understanding and agreement between the
Company and the Holder with respect to the subject hereof. Neither this
Debenture nor any term hereof may be amended, waived, discharged or terminated
other than by a written instrument signed by the Company and the Holder.

     20. Assignment, Etc. Subject to Section 8.8 of the Purchase Agreement, the
Holder (but not the Company) may without notice, transfer or assign this
Debenture or any interest herein and may mortgage, encumber or transfer any of
its rights or interest in and to this Debenture or any part hereof and, without
limitation, each assignee, transferee and mortgagee (which may include any
affiliate of the Holder) shall have the right to transfer or assign its
interest. Each such assignee, transferee and mortgagee shall have all of the
rights of the Holder under this Debenture. The Company agrees that, subject to
compliance with the Purchase Agreement, after receipt by the Company of written
notice of assignment from the Holder or from the Holder's assignee, all
principal, interest and other amounts which are then and thereafter become due
under this Debenture shall be paid to such assignee at the place of payment
designated in such notice. This Debenture shall be binding upon the Company and
its successors and affiliates and shall inure to the benefit of the Holder and
its successors and assigns.

     21. No Waiver. No failure on the part of the Holder to exercise, and no
delay in exercising any right, remedy or power hereunder shall operate as a
waiver thereof, nor shall any single or partial exercise by the Holder of any
right, remedy or power hereunder preclude any other or future exercise of any
other right, remedy or power. Each and every right, remedy or power hereby
granted to the Holder or allowed it by law or other agreement shall be
cumulative and not exclusive of any other, and may be exercised by the Holder
from time to time.

     22. Certificate. The Company shall, upon the written request at any time of
any Holder of Debentures, furnish or cause to be furnished to such Holder a
certificate prepared by the chief financial officer of Company setting forth any
adjustments or readjustments of the Conversion Price pursuant to this Debenture
and any right of the Holder to receive additional shares of Common Stock or any
other equity or debt security pursuant to Section 6.

     23. Notices. The Company shall distribute to the Holders of Debentures
copies of all notices, materials, annual and quarterly reports, proxy
statements, information statements and any other documents distributed generally
to the holders of shares of Common Stock of the Company, at such times and by
such method as such documents are distributed to such holders of such Common
Stock, but shall not directly or indirectly provide material non-public
information to the Holder without such Holder's prior written consent.

                                       18
<PAGE>   19

     24. Specific Enforcement. The Company agrees that irreparable damage would
occur in the event that any of the provisions of this Debenture were not
performed in accordance with their specific terms or were otherwise breached. It
is accordingly agreed that the Holders of Debentures shall be entitled to
specific performance, injunctive relief or other equitable remedies to prevent
or cure breaches of the provisions of this Debenture and to enforce specifically
the terms and provisions hereof, this being in addition to any other remedy to
which any of them may be entitled under agreement, at law or in equity.

     25. Miscellaneous. Unless otherwise provided herein, any notice or other
communication to a party hereunder shall be sufficiently given if in writing and
personally delivered, facsimiled or mailed to said party by certified mail,
return receipt requested, at its address set forth herein or such other address
as either may designate for itself in such notice to the other and
communications shall be deemed to have been received when delivered personally
or, if sent by mail or facsimile, then when actually received by the party to
whom it is addressed. Whenever the sense of this Debenture requires, words in
the singular shall be deemed to include the plural and words in the plural shall
be deemed to include the singular. Paragraph headings are for convenience only
and shall not affect the meaning of this document.

     26. GOVERNING LAW; CONSENT TO JURISDICTION. THIS DEBENTURE SHALL BE
GOVERNED BY AND CONSTRUED AND ENFORCED IN ACCORDANCE WITH THE LAWS OF THE STATE
OF NEW YORK APPLICABLE TO CONTRACTS TO BE EXECUTED AND PERFORMED ENTIRELY WITHIN
SUCH STATE. THE COMPANY (I) HEREBY IRREVOCABLY SUBMITS TO THE EXCLUSIVE
JURISDICTION OF THE STATE AND FEDERAL COURTS LOCATED IN NEW YORK COUNTY, NEW
YORK FOR THE PURPOSES OF ANY SUIT, ACTION OR PROCEEDING ARISING OUT OF OR
RELATED TO THIS DEBENTURE AND (II) HEREBY WAIVES, AND AGREES NOT TO ASSERT IN
ANY SUCH SUIT, ACTION OR PROCEEDING, ANY CLAIM THAT IT IS NOT PERSONALLY SUBJECT
TO THE JURISDICTION OF SUCH COURT, THAT THE SUIT, ACTION OR PROCEEDING IS
BROUGHT IN AN INCONVENIENT FORUM OR THAT THE VENUE OF THE SUIT, ACTION OR
PROCEEDING IS IMPROPER. THE COMPANY CONSENTS TO PROCESS BEING SERVED IN ANY SUCH
SUIT, ACTION OR PROCEEDING BY MAILING A COPY THEREOF TO SUCH PARTY AS PROVIDED
HEREIN AND AGREES THAT SUCH SERVICE SHALL CONSTITUTE GOOD AND SUFFICIENT SERVICE
OF PROCESS AND NOTICE THEREOF. NOTHING IN THIS PARAGRAPH SHALL AFFECT OR LIMIT
ANY RIGHT TO SERVE PROCESS IN ANY OTHER MANNER PERMITTED BY LAW.

                             SIGNATURE PAGE FOLLOWS

                                       19
<PAGE>   20

     IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed by an officer thereunto duly authorized.

                                       VISUAL DATA CORPORATION

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

      Signature page to 6% Convertible Debenture of VISUAL DATA CORPORATION

                                       20
<PAGE>   21

                                    EXHIBIT 1

                                PAYMENT STATEMENT

Date:______________

To: [NAME OF HOLDER OF DEBENTURE] ("HOLDER")

RE:  6% CONVERTIBLE DEBENTURE DUE DECEMBER __, 2003  ("DEBENTURE") OF VISUAL
DATA CORPORATION (THE "COMPANY"), IN THE OUTSTANDING PRINCIPAL AMOUNT OF
US$____________.

     The Company hereby irrevocably elects to pay interest on the Debenture, for
the Interest Payment Date indicated below, in the following manner (the Company
should check its selection):

     ____ cash interest; or

     ____ PIK Interest.

     ____ Interest Shares.

     Interest Payment Date: _________________________

     If the selection above is PIK Interest, the Company should fill in the
following:

     Outstanding Principal Amount prior
     to issuance of this Payment Statement:               US$_____________

     PIK Interest; or                                     US$_____________

     Outstanding Principal Amount after
     issuance of this Payment Statement:                  US$_____________

     If the selection above is Interest Shares, the Company should fill in the
following:

     Interest Conversion Price:                           US$_____________

     Number of Interest Shares:                           US$_____________

     The Company hereby certifies to the Holder, its successors and
assigns that the Outstanding Principal Amount due under the Debenture after
delivery of this Payment Statement equals the amount indicated below.
Capitalized terms used in this Payment Statement and not otherwise defined shall
have the meaning ascribed thereto in the Debenture.

                                       21
<PAGE>   22

     IN WITNESS WHEREOF, this Payment Statement has been duly executed and
delivered on the date first written above.

                                       VISUAL DATA CORPORATION

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

                                       22
<PAGE>   23

                                    EXHIBIT 2

                      (To be Executed by Registered Holder
                         in order to Convert Debenture)

                                CONVERSION NOTICE
                                       FOR
                 6% CONVERTIBLE DEBENTURE DUE DECEMBER __, 2003

     The undersigned, as Holder of the 6% Convertible Debenture Due December __,
2003 of VISUAL DATA CORPORATION (the "COMPANY"), in the outstanding principal
amount of U.S. $_____________ (the "DEBENTURE"), hereby elects to convert that
portion of the outstanding principal amount of the Debenture shown on the next
page into shares of Common Stock, $0.01 par value per share (the "COMMON
STOCK"), of the Company according to the conditions of the Debenture, as of the
date written below. The undersigned hereby requests that share certificates for
the Common Stock to be issued to the undersigned pursuant to this Conversion
Notice be issued in the name of, and delivered to, the undersigned or its
designee as indicated below. If shares are to be issued in the name of a person
other than the undersigned, the undersigned will pay all transfer taxes payable
with respect thereto. No fee will be charged to the Holder for any conversion,
except for transfer taxes, if any.

Conversion Information:      NAME OF HOLDER: ___________________________________

                         By:____________________________________________________
                             Print Name:
                             Print Title:

                             Print Address of Holder:
                             ___________________________________________________
                             ___________________________________________________

                             Issue Common Stock to: ____________________________
                             at: _______________________________________________

                             Electronically transmit and credit Common Stock to:
                             _____________ at: _________________________________

                             ___________________________________________________
                             Date of Conversion

                             ___________________________________________________
                             Applicable Conversion Rate

                THE COMPUTATION OF THE NUMBER OF COMMON SHARES TO
                  BE RECEIVED IS SET FORTH ON THE ATTACHED PAGE

<PAGE>   24

PAGE 2 TO CONVERSION NOTICE FOR:  ______________________________________________
                                               (NAME OF HOLDER)

              COMPUTATION OF NUMBER OF COMMON SHARES TO BE RECEIVED

<TABLE>
<S>                                                                             <C>
A.       Outstanding Principal Amount converted:                                $
                                                                                 --------------
B.       Accrued, unpaid interest on Outstanding Principal Amount converted:    $
                                                                                 --------------
TOTAL DOLLAR AMOUNT CONVERTED (TOTAL OF A + B)                                  $
                                                                                 --------------

                                                                                ================

CONVERSION PRICE                                                                $
                                                                                 --------------

Number of Shares of Common Stock   =    Total dollar amount converted     =     $
                                        -----------------------------            --------------
                                              Conversion Price                  $

NUMBER OF SHARES OF COMMON STOCK   =    _____________________________
</TABLE>

If the conversion is not being settled by DTC, please issue and deliver _____
certificate(s) for shares of Common Stock in the following amount(s):

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

Please issue and deliver _____ new Debenture(s) in the following amounts:

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

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