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                                                                   Exhibit 10.19

                SUPPLEMENTAL LIMITED LIABILITY COMPANY AGREEMENT


                  This SUPPLEMENTAL LIMITED LIABILITY COMPANY AGREEMENT, dated
as of March 21, 2000 (the "Agreement"), is entered into by and between WBT
Holdings LLC, a Dela ware limited liability company (the "Company"), and the
individual listed on the signature page hereto (the "Individual").

                  WHEREAS, the Company desires to grant Underfunded Units (the
"Units") to an additional member of the Company's management and the Individual
desires to accept such grant; and

                  WHEREAS, the Company and the Individual desire to enter into
this Agreement in order to set forth their understanding with respect to certain
voting arrangements, transfer rights and other matters relating to the
Individual's ownership of the Units and to acknowledge that the Units are
subject to, and governed by, the Limited Liability Company Agreement (as defined
below).

                  NOW, THEREFORE, in consideration of the mutual promises
contained in this Agreement and other good and valuable consideration the
receipt and sufficiency of which is hereby acknowledged, the parties to this
Agreement agree as follows:

                                    ARTICLE I

              INCORPORATION OF LIMITED LIABILITY COMPANY AGREEMENT

                  SECTION 1.1 Documentation With Respect to the Shares. The
Individual hereby acknowledges that the Units are subject to various agreements,
including with out limitation, the Limited Liability Company Agreement, dated as
of February 10, 2000 (as the same may be amended from time to time, the "Limited
Liability Company Agreement"), by and among the Company and the Members of the
Company as set forth therein. Terms not defined herein shall have the meaning
set forth in the Limited Liability Company Agreement.

                  SECTION 1.2 Access to Information. The Individual (i) has
reviewed the Limited Liability Company Agreement and the other materials
furnished to him in

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connection with the transactions contemplated hereby and (ii) has been granted
the opportunity to ask questions of, and has received answers from,
representatives of the Company and its affiliates concerning the terms and
conditions of the Units and has been granted the opportunity to obtain any
additional information that he deems necessary to verify the accuracy of the
information contained in the Limited Liability Company Agreement and such other
materials.

                  SECTION 1.3 General. Upon the execution of this Agreement, the
Individual shall be deemed, in accordance with Article XIV of the Limited
Liability Company Agreement, to have the same rights and obligations as a Member
(as defined therein) for purposes of the Limited Liability Company Agreement.
The Individual hereby agrees to be bound by, and agrees that the Units are
subject to, and governed by, the terms and conditions of the Limited Liability
Company Agreement. The Individual, in accordance with Article XIV of the Limited
Liability Company Agreement, is hereby deemed to be a Management Member (as
defined therein) with respect to the Units (and only such Units) which are
subject to, or governed by, this Agreement for all purposes of the Limited
Liability Company Agreement. The Individual hereby agrees that the Units are
Underfunded Units. Pursuant to Section 14.3 of the Limited Liability Company
Agreement, this Agreement is effective as of the date hereof.

                  SECTION 1.4 Conflict. In the event of a conflict between the
terms hereof and the Limited Liability Company Agreement, the terms of the
Limited Liability Company Agreement shall control.


                                   ARTICLE II

                                  Miscellaneous

                  SECTION 2.1 After-Acquired Units. All of the provisions of
this Agreement shall apply to all of the securities of the Company now owned or
which may be issued or Transferred (as defined in the Limited Liability Company
Agreement) hereafter to the Individual in consequence of any additional
issuance, grant, purchase (including, without limitation, pursuant to options to
purchase capital stock of the Company), exchange, conver-


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sion, or reclassification of securities, corporate reorganization, or any other
form of recapitalization, consolidation, merger, unit split or unit dividend,
or which are acquired by the Individual in any other manner (all of which shall
be deemed to be "Units" hereunder); provided, however, that, notwithstanding
anything contained herein to the contrary, no Units, rights to acquire Units or
other securities of the Company which are owned by the Individual or any entity
controlled or created by the Individual prior to the date hereof shall be
subject to, or governed by, this Agreement.

                  SECTION 2.2 Specific Performance. The parties hereto
acknowledge that irreparable damage would result if this Agreement is not
specifically enforced and that, therefore, the rights and obligations of the
parties under this Agreement may be enforced by a decree of specific performance
issued by a court of competent jurisdiction, and appropriate injunctive relief
may be applied for and granted in connection therewith. Such remedies shall,
however, be cumulative and not exclusive and shall be in addition to any other
remedies which any party may have under this Agreement or otherwise.

                  SECTION 2.3 Terms of Agreement. This Agreement shall become
effective on the date hereof and shall continue in full force and effect until
the date on which the Limited Liability Company Agreement terminates.

                  SECTION 2.4 Successors and Assigns. All the terms and
provisions of this Agreement shall inure to the benefit of and be binding upon
the parties hereto and their respective successors and assigns; provided, how
ever, no party hereto may assign this Agreement or his or its rights or
obligations hereunder without the prior written consent of the other party
hereto.

                  SECTION 2.5 Entire Agreement. This Agreement and the Limited
Liability Company Agreement constitute the complete understanding and agreement
among the par ties hereto with respect to the subject matter hereof and this
Agreement can be amended, supplemented or changed, and any provision hereof can
be waived, only by written instrument making specific reference to this
Agreement signed by the party against whom enforcement of any such amendment,
supplement, modification or waiver is sought.




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                  SECTION 2.6 Approvals and Consents. The Individual hereby
agrees, for himself, his heirs and legal representatives(s), to prepare, execute
and deliver or cause to be prepared, executed and delivered such further
instruments and documents, and to take such other actions as may be reasonably
required to more effectively carry out the intent and purposes of this Agreement
and the Limited Liability Company Agreement and the transactions contemplated
hereby and thereby.

                  SECTION 2.7 Notices. All notices, requests, demands and other
communications which are required or may be given hereunder shall be in writing
and shall be deemed to have been duly given to a party if delivered personally
or mailed by certified or registered mail, return receipt requested, postage
prepaid, or if given by telex or other telegraphic means, to such party at his
or its address set forth in Schedule A hereto. Any such notice shall for all
purposes of this Agreement be deemed to have been given, and received by the
addressee, on the date of such personal delivery or telex or telegraphic notice
or five (5) days after any such mailing thereof.

                  SECTION 2.8 Governing Law. This Agreement shall be governed by
and construed in accordance with the laws of the State of Delaware.

                  SECTION 2.9 Severability. If any provision of this Agreement
or the application of any such provision to any person or circumstances shall
be held invalid by a court of competent jurisdiction, the remainder of this
Agreement, including the remainder of the provision held invalid, or the
application of such provision to persons or circumstances other than those as to
which it is held invalid, shall not be affected thereby.

                  SECTION 2.10 Counterparts. This Agreement may be executed in
one or more counterparts, each of which shall be deemed to be an original, but
all of which together shall constitute one and the same instrument.

                  SECTION 2.11 Headings. All section headings herein are for
convenience of reference and are not part of this Agreement, and no construction
or interference shall be derived therefrom.




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                  IN WITNESS WHEREOF, the parties hereto have hereunto set their
hands as of the date first set forth above.


                                              __________________________________
                                              Name: Bruce Barnes


                                              WBT HOLDINGS LLC



                                              By:_______________________________
                                                 Name:  Robert Fogelson
                                                 Title:



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                                                                      Schedule A

Individual:

Bruce Barnes






Company:

WBT Holdings LLC




<TABLE>
<CAPTION>
           Units Granted                      Underfunded Amount                Capital Account
           -------------                      ------------------                ---------------
<S>                                           <C>                               <C>
              300,000                                   $4 per Unit                    $0
              200,000                                $[ ]* per Unit
</TABLE>



--------

*        Amount equal to the per share price in the IPO.


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