<PAGE>

                                                                    EXHIBIT 10.2

                      DO NOT DESTROY THIS PROMISSORY NOTE.
                      ------------------------------------

WHEN PAID IN FULL, THIS NOTE, TOGETHER WITH THE SECURITY INSTRUMENTS SECURING
THE SAME, SHOULD BE MARKED "CANCELED" BY LENDER AND DELIVERED TO BORROWER AS
RECEIPT OF ALL AMOUNTS OWING UNDER THIS NOTE.

THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED ("SECURITIES ACT") OR THE SECURITIES LAWS OF ANY STATE AND ARE BEING
OFFERED AND SOLD IN RELIANCE ON EXEMPTIONS FROM THE REGISTRATION REQUIREMENTS OF
THE SECURITIES ACT AND SUCH LAWS.  THESE SECURITIES HAVE NOT BEEN APPROVED OR
DISAPPROVED BY THE SECURITIES AND EXCHANGE COMMISSION, ANY STATE SECURITIES
COMMISSION, THE AMERICAN STOCK EXCHANGE OR OTHER REGULATORY AUTHORITY, NOR HAVE
ANY OF THE FOREGOING AUTHORITIES PASSED UPON OR ENDORSED THE MERITS OF THIS
OFFERING.

THESE SECURITIES AND ANY SHARES ISSUED UPON THE CONVERSION TERMS SET FORTH
HEREIN ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE AND MAY NOT BE
TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE SECURITIES ACT AND THE
APPLICABLE STATE SECURITIES LAWS, PURSUANT TO REGISTRATION OR EXEMPTION
THEREFROM.

                                 PROMISSORY NOTE
                                 ---------------
                             (Convertible & Secured)
                                                            New York, New York
                                                              December 4, 2001

FOR VALUE RECEIVED, LAIDLAW GLOBAL CORPORATION, a Delaware corporation
(hereinafter called "Borrower"), hereby promises to pay in lawful money of the
United States of America and in immediately available funds, to the order of
Third Security, LLC, a Virginia limited liability company ("Lender"), at such
place as Lender shall specify, on the Maturity Date defined below, the original
principal sum of One Million Five Hundred Thousand Dollars ($1,500,000) (the
"Loan Amount"), which Loan Amount may be increased (as adjusted, the "Loan
Amount") pursuant to the terms of the Call and Put Option Agreement, dated as of
the date hereof, between Borrower and Lender (the "Call and Put Option
Agreement"), together with accrued interest as provided herein, if any, and in
accordance with the following provisions:

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<PAGE>

1.  Term; Principal Payments; Maturity. The Loan Amount, together with accrued
    ----------------------------------
interest as provided herein, if any, is payable on the earlier of (i) 45 days
(excluding in determining the 45 days the days from December 15 through December
31, inclusively) after delivery of written notice from Lender to Borrower of its
decision to abandon its right to acquire all of the Purchased Shares (as defined
in the LOI (as defined below)) or (ii) April 1, 2003 (the "Maturity Date").

2.  Calculation of Interest. The aggregate outstanding principal balance of this
    -----------------------
Note shall accrue simple interest at 8 1/2% per annum. Interest shall be
calculated on the unpaid principal balance hereof on the basis of the actual
number of days elapsed and based on a 360-day year and shall accrue until the
Maturity Date or conversion of the entire principal amount of this Note.
Interest (including any default interest at the rate set forth in Paragraph 11
hereof, if any) shall accrue and be payable under this Note whether or not
Borrower, its successors or assigns, should avail themselves of the protection
of the United States bankruptcy courts in any manner.  All accrued and unpaid
interest shall be payable in cash regardless of any conversion of this Note.

3.  Interest Payments. Borrower shall not be required to make any payments of
    -----------------
accrued interest until the earlier of (i) the Maturity Date or (ii) the
conversion of the entire principal amount of this Note, at which time the entire
Loan Amount, together with all accrued but unpaid interest thereon, shall be due
and payable to Lender in full.

4.  Place of Payment. All payments due under this Note, shall be mailed, wired
    ----------------
or delivered to Lender at such place or address as Lender of this Note may
specify in writing to Borrower.

5.  Purpose.  Borrower and Lender acknowledge that this Note is being given as
    -------
part of a transaction contemplated by a Letter of Intent ("LOI") dated December
3, 2001 between the parties.  This Note reflects the delivery of funds as
provided by the LOI and the parties anticipate that the Note will be superceded
and replaced by a formal agreement between the parties, negotiated in good
faith, in furtherance of the LOI (the "Definitive Agreement").

6.  Security.
    --------

    6.1.  As a condition to Lender accepting this Note from Borrower, and as
security therefore, Borrower shall grant to Lender a general security interest
in and to all of the shares of common stock owned by Borrower in H&R Acquisition
Corp. (which property and assets are further identified and defined as the
"Collateral" in the Pledge Agreement, as defined below).

    6.2.  The terms of the security interest granted to Lender is evidenced and
further defined by that certain Pledge Agreement and accompanying UCC Financing
Statement(s), if any, executed and delivered concurrently with this Note by and
between Borrower and Lender (collectively, the "Pledge Agreement")

7.  Terms of Conversion.
    -------------------

    7.1.  Lender shall have the right, at any time or times (i) subsequent to
the Maturity

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<PAGE>

Date so long as the Loan Amount has not been repaid, (ii) after a
default not cured as provided for herein or in the Pledge Agreement, or (iii)
with the written consent of Borrower, to elect in lieu of collection hereon or
any other relief, to convert all of the unpaid portion of the Loan Amount into
shares of the common stock of Borrower (the "Common Stock") at the Conversion
Price hereinafter defined.  In addition, Lender shall have the right, at any
time or times after execution of the Definitive Agreement to convert an amount
of the unpaid portion of the Loan Amount into shares of Common Stock equal to
the number of shares comprising the Initial Shares (as defined in the LOI) in
excess of the Option Shares (as defined in the LOI) purchased by Lender, at the
Conversion Price hereinafter defined.

          7.1.1. "Conversion Price" shall mean that amount fixed in the
Definitive Agreement for the acquisition of Common Stock by Lender or until such
time as the Definitive Agreement is entered into between Lender and Borrower,
the amount specified in the Call and Put Option Agreement.

          7.1.2. The Conversion Price in effect at any time and the number and
shares of Common Stock purchasable upon the exercise of the Note shall be
subject to adjustment from time to time upon the happening of certain events as
follows:

               7.1.2.1. In case Borrower shall (i) declare a dividend or make a
distribution on its outstanding shares of Common Stock in shares of Common
Stock, (ii) subdivide or reclassify its outstanding shares of Common Stock into
a greater number of shares, or (iii) combine or reclassify its outstanding
shares of Common Stock into a smaller number of shares, the Conversion Price in
effect at the time of the record date for such dividend or distribution or of
the effective date of such subdivision, combination or reclassification shall be
adjusted so that it shall equal the price determined by multiplying the
Conversion Price by a fraction, the denominator of which shall be the number of
shares of Common Stock outstanding after giving effect to such action, and the
numerator of which shall be the number of shares of Common Stock outstanding
immediately prior to such action. Such adjustment shall be made successively
whenever any event listed above shall occur.

               7.1.2.2. In case Borrower shall (i) sell shares of Common Stock
at a price per share less than the Conversion Price then applicable, or (ii)
issue any security convertible into shares of Common Stock with a conversion
price per share less than the Conversion Price then applicable, then in any and
every such event, the Conversion Price shall be reduced and shall be equal to
such lower sales or conversion price.

               7.1.2.3. Whenever the Conversion Price is adjusted, as herein
provided, Borrower shall promptly cause a notice setting forth the adjusted
Conversion Price and adjusted number of shares issuable upon conversion of the
Note to be delivered to Lender as provided herein. Borrower may retain a firm of
independent certified public accountants selected by the Board of Directors (who
may be the regular accountants employed by Borrower) to make any computation
required by this Section, and a certificate signed by such firm shall be
conclusive evidence of the correctness of such adjustment.

                                       3
<PAGE>

    7.2.  To exercise the aforesaid conversion right, Lender shall deliver to
Borrower at its principal office a Notice of Conversion, attached hereto as the
"Notice of Conversion", and Borrower shall deliver the Shares into which all or
part of the Note has been converted and the outstanding Loan Amount shall be
reduced by the amount so converted.

    7.3.  Limitation on Shares.  The issuance of any shares of Common Stock on
          --------------------
conversion of this Note as set forth herein shall be subject to all applicable
rules and regulations of the Securities Act, the Securities and Exchange
Commission, any State Securities Commission, the American Stock Exchange or any
other regulatory authority having jurisdiction thereon.  Borrower agrees to use
its best efforts and to cooperate with Lender in obtaining compliance with such
authority, rules and regulations to give effect to the right of conversion.

8.  Covenants and Agreements of Borrower. Until this Note has been paid in full
    ------------------------------------
as provided herein, Borrower hereby covenants and agrees with Lender as follows:

    8.1.  Borrower will at all times take or cause to be taken all such action
as may from time to time be necessary to maintain, preserve, and renew its
corporate existence in good standing under the laws of the State of Delaware.

    8.2.  Borrower agrees to perform, keep and observe all of the terms,
conditions, covenants, agreements, warranties or representations contained in
this Note, the Pledge Agreement and in any other agreement regarding the
Collateral to which it is bound as though fully set forth herein and agreed to
hereby.

    8.3.  Borrower shall at all times reserve and keep available out of its
authorized but unissued shares of Common Stock for the purpose of effecting the
conversion of this Note such number of its shares of Common Stock as shall from
time to time be sufficient to effect the conversion of this Note; and if at any
time the number of authorized but unissued shares of Common Stock shall not be
sufficient to effect the conversion of the entire outstanding principal amount
of this Note, in addition to such other remedies as shall be available to the
holder of this Note, Borrower will use its best efforts to take such corporate
action as may, in the opinion of its counsel, be necessary to increase its
authorized but unissued shares of Common Stock to such number of shares as shall
be sufficient for such purposes.

9.  Default of Borrower. Any one or more of the following shall constitute an
    -------------------
"event of default" by Borrower under the terms of this Note:

    9.1.  If Borrower fails to pay any payment, whether at Maturity or
otherwise, of principal and/or interest upon the due date thereof, if such
default continues and remains uncured for a period of five days after written
notice from Lender; and/or

    9.2.  If Borrower defaults in the performance or observance of any of the
covenants, conditions or agreements set forth in this Note, the Pledge
Agreement, the LOI or any other credit or loan agreement pursuant to which
Borrower has issued debt securities or borrowed money,

                                       4
<PAGE>

and if such default continues and remains uncured for any curative period
provided for therein; and/or

    9.3.  The institution by Borrower of proceedings to be adjudicated as
bankrupt or insolvent, or the consent by it to institution of bankruptcy or
insolvency proceedings against it or the filing by it of a petition or answer or
consent seeking reorganization or release under the Federal Bankruptcy Act, or
any other applicable federal or state law, or the consent by it to the filing of
any such petition or the appointment of a receiver, liquidator, assignee,
trustee or other similar official of Borrower, or of any substantial part of its
property, or the making by it of an assignment for the benefit of creditors, or
the taking of corporate action by Borrower in furtherance of any such action, or
the admission in writing of its inability to pay its debts generally as they
become due; and/or

    9.4.  If, within 60 days after the commencement of an action against

Borrower (and service of process in connection therewith on Borrower) seeking
any bankruptcy, insolvency, reorganization, liquidation, dissolution or similar
relief under any present or future statute, law or regulation, such action shall
not have been resolved in favor of Borrower or all orders or proceedings
thereunder affecting the operations or the business of Borrower stayed, or if
the stay of any such order or proceeding shall thereafter be set aside, or if,
within 60 days after the appointment without the consent or acquiescence of
Borrower of any trustee, receiver or liquidator of Borrower or of all or any
substantial part of the properties of Borrower, such appointment shall not have
been vacated.

10.  Lender's Remedies for Default. In the event of a default described in
     -----------------------------
Paragraph 9 above, and after any applicable notice and/or curative period
specified therein, at the option of Lender, and upon written demand, Lender may
do one or any of the following:

    10.1. Accelerate the Maturity Date of this Note and declare the entire
outstanding balance hereof, including all fees and costs (if any), principal and
accrued but unpaid interest thereon, immediately due and payable in full; and/or

    10.2. Exercise any other of its rights or remedies available to Lender under
the terms of the Pledge Agreement, as well as all other rights and remedies
Lender shall have as a secured party under the Uniform Commercial Code.

    10.3. Each of the options, rights and remedies provided herein or available
at law or in equity which may be exercised by Lender, may be exercised
separately or concurrently with any one or more other options, rights or
remedies. Failure to exercise any option, right or remedy shall not constitute a
waiver of the right of Lender to exercise such option, right or remedy in the
event of or with respect to any prior, subsequent or concurrent transaction or
occurrence of the same or a different kind or character.

11.  Increase in Interest Rate. From and after the maturity of this Note,
     -------------------------
whether on the Maturity Date or as a result of an acceleration of the principal
and interest by reason of an event

                                       5
<PAGE>

of default under this Note, the entire outstanding principal balance hereunder
and all accrued but unpaid interest thereon shall automatically bear interest
(in place of the interest rate specified above) at the rate of 12% per annum (or
1% per month).

12.  Conformity With Usury Laws. Notwithstanding anything to the contrary
     --------------------------
contained herein, the amount of interest payable under the terms of this Note
shall in no event exceed the maximum amount of interest permitted to be charged
by law.  Any interest so paid by Borrower in excess of the maximum amount of
interest permitted by law shall be deemed to have been payments of principal.

13.  Attorneys' Fees and Costs. If any action or proceeding, including
     -------------------------
arbitration, is commenced to collect this Note or any part thereof at law, in
equity, in bankruptcy or otherwise, or if Borrower's obligations hereunder or
any part thereof are placed in the hands of attorneys for collection, the court
or arbitrator in such action or proceeding shall award Lender, or any other
holder of this Note, in addition to any other relief granted, (i) the actual
reasonable attorneys' which the prevailing party has paid or is obligated to
pay; and (ii) all costs and expenses, not merely recoverable costs, which the
prevailing party has paid or is obligated to pay. The court or arbitrator may
reduce such actual reasonable attorneys' fees, costs and expenses only to the
extent that the court or arbitrator determines that such amounts were
unnecessarily incurred. In addition, the parties agree that if any dispute
between the parties results in a judgment in favor of either party, such party
shall be entitled to recover from the other all reasonable attorneys' fees and
costs incurred by it in enforcing such judgment. This provision is intended to
be severable from any other provision of this Note and is not to be deemed
merged in the judgment.

14.  No Waiver; Extension of Time for Repayment. Lender of this Note may extend
     ------------------------------------------
the time for payment, postpone the enforcement hereof or grant any other
indulgences without affecting or diminishing Lender's right to recourse against
Borrower or any endorsers, sureties or guarantors, which right is expressly
reserved.

15.  Binding Effect; Assignability. The terms and provisions hereof shall inure
     -----------------------------
to the benefit of and be binding upon Borrower and Lender and their respective
successors, and assigns; provided, however, Borrower's obligations hereunder are
nontransferable and non assignable without the prior written consent of Lender.
Any person who assumes the obligations under this Note shall also be obligated
to keep of the promises made in this Note. Lender may enforce its rights under
this Note against each person individually or against all of them together,
meaning that any one of them may be required to pay all of the amounts owed
under this Note.

16.  Severability.  In the event any one or more of the provisions contained in
     ------------
this Note, or any application thereof shall be invalid or rendered unenforceable
in any effect, the validity, legality and enforceability of the remaining
provisions contained herein and the application thereof shall not in any way be
affected or impaired thereby.

17.  Governing Law. This Note and any exhibits or supplements hereto shall be
     -------------
deemed entered into in the State of New York.   This Note and the rights of the
parties hereunder shall be

                                       6
<PAGE>

governed by and construed in accordance with the law of the State of New York
without giving effect to any conflict of law provision.

18.  Errors and Omissions Compliance.  Borrower acknowledges that in
     -------------------------------
consideration of the delivery of the Loan Amount, Borrower agrees to cooperate
promptly with Lender and its agents in the correction or completion of the
documents related to the loan, if deemed necessary or desirably by Lender.
Borrower understands that this may include correction of names of parties,
correction or execution of a new note or other agreement evidencing the
indebtedness or other security agreement to reflect the agreed terms as same may
be revised.  Failure to so cooperate shall be deemed an event of default under
Paragraph 10, above.

19.  Waiver.  Except as herein provided, Borrower waives demand for payment,
     ------
presentment, protest, notice of protest and non-payment, or other notice of
default, notice of acceleration and intention to accelerate, and agrees that its
liability under this Note shall not be affected by any renewal or extension in
the time of payment hereof, or by any indulgences, or by any release or change
in any security for the payment of this Note, and hereby consents to any and all
renewals, extensions, indulgences, releases or changes, regardless of the number
of such renewals, extensions, indulgences, releases or changes.

                                       7
<PAGE>

     IN WITNESS WHEREOF, Borrower has caused this Promissory Note (Convertible &
Secured) to be executed and delivered by a duly authorized officer as of the day
and year first above written.

                         LAIDLAW GLOBAL CORPORATION,
                         Borrower:



                         By:  /s/ Roger E. Bendelac
                              ------------------------------
                              Name: Roger E. Bendelac
                              Title: Chairman

                                       8
<PAGE>

                              NOTICE OF CONVERSION



     The undersigned hereby irrevocably elects to convert the attached
Convertible Note to the extent of purchasing shares of Common Stock of Laidlaw
Global Corporation in accordance with the terms of conversion set forth therein
and hereby surrenders the Convertible Note in payment of the actual Conversion
Price thereof.



Date:_________________, 200_

THIRD SECURITY, LLC




By:  ___________________________________
     Name:
     Title:

                                       9