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                                 EXHIBIT 10.45


                           STOCK PURCHASE AGREEMENT


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                               TABLE OF CONTENTS

                                                                  Page No.
                                                                  --------

     1.   Purchase and Sale of Stock................................  1
          1.1  Sale and Issuance of Stock...........................  1
          1.2  The Closing..........................................  1

     2.   Representations and Warranties of the Company.............  1
          2.1  Organization and Good Standing.......................  1
          2.2  Authorization........................................  1
          2.3  Valid Issuance of Stock..............................  2
          2.4  Registration Statement...............................  2

     3.   Representations and Warranties of the Investor............  2
          3.1  Authorization........................................  2
          3.2  Investigation........................................  2
          3.3  Qualified Institutional Buyer........................  2
          3.4  Purchase Entirely for Own Account....................  2
          3.5  Restricted Securities................................  3

     4.   Conditions to the Investor's Obligation at Closing........  3
          4.1  Representations and Warranties.......................  3
          4.2  Securities Laws......................................  3
          4.3  Authorizations.......................................  3
          4.4  Initial Public Offering of Common Stock..............  3
          4.5  No Material Adverse Change...........................  3

     5.   Conditions to the Company's Obligations at Closing........  3
          5.1  Representations and Warranties.......................  3
          5.2  Securities Laws......................................  4
          5.3  Authorizations.......................................  4
          5.4  Initial Public Offering of Common Stock..............  4
          5.5  Payment of Purchase Price............................  4

     6.   Covenants of the Company and the Investor.................  4
          6.1  Agreement Not Transfer...............................  4
          6.2  Market Stand-Off.....................................  4
          6.3  Notice of Intention to Transfer......................  4
          6.4  Registration of Stock................................  5
          6.5  Publicity............................................  5

     7.   Miscellaneous.............................................  5
          7.1  Governing Law........................................  5
          7.2  Survival; Additional Securities......................  5
          7.3  Successors and Assigns...............................  5
          7.4  Entire Agreement.....................................  6
          7.5  Notices..............................................  6
          7.6  Amendments and Waivers...............................  6
          7.7  Legal Fees...........................................  6


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           7.8  Expenses...............................................  6
           7.9  Titles and Subtitles...................................  6
          7.10  Counterparts...........................................  6
          7.11  Severability...........................................  6
          7.12  Confidentiality........................................  6
          7.13  Termination............................................  7


                                      ii
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                           STOCK PURCHASE AGREEMENT

     THIS STOCK PURCHASE AGREEMENT is made as of the 3rd day of February, 2000,
by and between FirstWorld Communications, Inc., a Delaware corporation (the
"Company") and SAIC Venture Capital Corporation, a Nevada corporation (the
"Investor").

     WHEREAS, the Investor has indicated a desire to purchase the number of
shares of the Company's Series B Common Stock ("Common Stock") obtained by
dividing $19,500,000 by 93% of the per share price paid by the public for the
Company's Common Stock in the Company's initial public offering (the "IPO").

     WHEREAS, the Company has indicated a desire to sell the number of shares of
the Company's Common Stock obtained by dividing $19,500,000 by 93% of the per
share price paid by the public for the Company's Common Stock in the Company's
IPO to the Investor on the terms set forth herein.

     WHEREAS, the Company and the Investor have agreed that this Agreement shall
constitute the entire understanding and agreement between the parties with
regard to the subject matter hereof.

     NOW, THEREFORE, THE PARTIES HERETO AGREE AS FOLLOWS:

1.   Purchase and Sale of Stock.
     -------------------- -----

     1.1   Sale and Issuance of Stock.  Subject to the terms and conditions of
this Agreement, the Company agrees to sell to the Investor and the Investor
agrees to purchase from the Company the number of shares of the Company's Common
Stock obtained by dividing $19,500,000 by 93% of the per share price paid by the
public for the Company's Common Stock in the Company's IPO (the "Stock"), having
the rights, preferences, privileges and restrictions set forth in the Amended
and Restated Certificate of Incorporation of the Company (the "Restated
Certificate") on file with the Delaware Secretary of State as of the Closing (as
defined below).

     1.2   The Closing.  The purchase and sale of the Stock shall be held at the
Company's offices immediately following the closing of the Company's IPO (the
"Closing").  At the Closing, the Company will deliver the Stock to the Investor
against payment of the purchase price therefor by check payable to the order of
the Company or by wire transfer.  The per share purchase price for the Stock
shall be 93% of the per share price paid by the public for the Company's Common
Stock in the IPO.

2.   Representations and Warranties of the Company. Except as set forth on the
schedule of exceptions delivered herewith, the Company hereby represents and
warrants to the Investor that:

     2.1   Organization and Good Standing. The Company is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Delaware and has all requisite corporate power and authority to carry on its
business as now conducted. The Company is duly qualified to transact business
and is in good standing in each jurisdiction in which the failure to so qualify
would have a material adverse effect on its business or properties.

     2.2   Authorization.  All corporate action on the part of the Company, its
officers, directors and stockholders necessary for the authorization, execution
and delivery of this Agreement, the performance of all obligations of the
Company hereunder, and the authorization, issuance, sale and delivery of the
Stock has been taken or will be taken prior to the Closing, and this Agreement
constitutes a valid and

                                       1
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legally binding obligation of the Company, enforceable in accordance with its
terms, except (i) as limited by applicable bankruptcy, insolvency,
reorganization, moratorium, and other laws of general application affecting
enforcement of creditors' rights generally and (ii) as limited by laws relating
to the availability of specific performance, injunctive relief, or other
equitable remedies.

     2.3   Valid Issuance of Stock. The Stock, when issued, sold and delivered
in accordance with the terms hereof for the consideration expressed herein, will
be duly and validly issued, fully paid and nonassessable and will be free of
restrictions on transfer other than restrictions on transfer under this
Agreement and under applicable state and federal securities laws. Subject in
part to the truth and accuracy of the Investor's representations set forth in
Section 3 of this Agreement, the offer, sale and issuance of the Stock as
contemplated by this Agreement are exempt from the registration requirements of
any applicable state and federal securities laws.

     2.4   Registration Statement. The Company's registration statement on Form
S-1, as amended, (including any amendments or supplements thereto) (the
"Registration Statement") shall not, at the time the Registration Statement is
declared effective by the Securities and Exchange Commission ("SEC"), contain
any untrue statement of a material fact or omit to state any material fact
necessary in order to make the statements therein, in light of the circumstances
under which they were made, not misleading.  The Company has provided Investor
with a copy of the Registration Statement as filed with the SEC on December 22,
1999 and will provide Investor with a copy of the Registration Statement as
filed with the SEC immediately prior to the Closing.

3.   Representations and Warranties of the Investor. The Investor hereby
represents and warrants that:

     3.1   Authorization. This Agreement constitutes the valid and legally
binding obligation of the Investor, enforceable in accordance with its terms,
subject to laws of general application relating to bankruptcy, insolvency and
the relief of debtors and by general principles of equity.

     3.2   Investigation. The Investor acknowledges that it has had an
opportunity to discuss the business, affairs and current prospects of the
Company with the Company's chief executive officer. The Investor further
acknowledges having had access to information about the Company that it has
requested or considers necessary for purposes of purchasing the Stock. The
foregoing, however, does not limit or modify the representations and warranties
of the Company in Section 2 of this Agreement or the right of the Investors to
rely thereon.

     3.3   Qualified Institutional Buyer. The Investor is a "Qualified
Institutional Buyer" as such term is defined in Rule 144A of the rules and
regulations promulgated under the Securities Act of 1933, as amended.

     3.4   Purchase Entirely for Own Account. This Agreement is made with the
Investor in reliance upon the Investor's representation to the Company, which by
the Investor's execution of this Agreement the Investor hereby confirms, that
the Stock will be acquired for investment for the Investor's own account, not as
a nominee or agent, and not with a view to the resale or distribution of any
part thereof, and that the Investor has no present intention of selling,
granting any participation in, or otherwise distributing the same.  Neither the
Investor nor Science Applications International Corporation, a Delaware
Corporation ("SAIC") nor any entity controlled by SAIC has a present intention
of participating in the formulation, determination or direction of the basic
business decisions of the Company or any entities controlled by the Company.

                                       2
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     3.5   Restricted Securities. Investor understands that the shares of Stock
it is purchasing are characterized as "restricted securities" under the federal
securities laws inasmuch as they are being acquired from the Company in a
transaction not involving a public offering and that under such laws and
applicable regulations such securities may be resold without registration under
the Act, only in certain limited circumstances.  In this connection, Investor
represents that it is familiar with SEC Rule 144, as presently in effect, and
understands the resale limitations imposed thereby and by the Act.

4.   Conditions to the Investor's Obligation at Closing. The obligation of the
Investor to purchase the Stock at the Closing is subject to the fulfillment to
the Investor's satisfaction on or prior to the Closing of the following
conditions:

     4.1   Representations and Warranties. Except as set forth on the schedule
of exceptions delivered herewith, the representations and warranties made by the
Company in Section 2 hereof shall be true and correct when made, and shall be
true and correct as of the Closing with the same force and effect as if they had
been made on and as of such date. The Chief Executive Officer of the Company
shall deliver at the Closing a certificate stating that the condition specified
in the preceding sentence has been fulfilled.

     4.2   Securities Laws.  The offer and sale of the Stock to the Investor
pursuant to this Agreement shall be exempt from the registration requirements of
the Securities Act of 1933, as amended (the "Act") and qualification
requirements of all applicable state securities laws.

     4.3   Authorizations. All authorizations, approvals or permits, if any, of
any governmental authority or regulatory body that are required in connection
with the lawful issuance and sale of the Stock pursuant to this Agreement shall
have been duly obtained and shall be effective on and as of the Closing.

     4.4   Initial Public Offering of Common Stock. The closing of the initial
public offering of the Company's Series B Common Stock shall have occurred.

     4.5   No Material Adverse Change. There shall have been no material adverse
change in the condition (financial or otherwise), business, business assets, or
results of operations of the Company since the date of this Agreement; provided,
however, that for purposes of determining whether there shall have been any such
material adverse change, (i) any adverse change resulting from or relating to
general business or economic conditions shall be disregarded, (ii) any adverse
change resulting from or relating to conditions generally affecting the industry
in which the Company competes shall be disregarded, and (iii) any adverse change
resulting from or relating to the taking of any action contemplated by this
Agreement shall be disregarded.

5.   Conditions to the Company's Obligations at Closing. The obligation of
the Company to sell the Stock at the Closing is subject to the fulfillment to
the Company's satisfaction on or prior to the Closing of the following
conditions:

     5.1   Representations and Warranties. Except as set forth on the schedule
of exceptions delivered herewith, the representations and warranties of the
Investor contained in Section 3 hereof shall be true as of the Closing with the
same force and effect as if they had been made on and as of such date. The
President or Secretary of the Investor shall deliver at the Closing a
certificate stating that the condition specified in the preceding sentence has
been fulfilled.

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     5.2   Securities Laws. The offer and sale of the Stock to the Investor
pursuant to this Agreement shall be exempt from the registration requirements of
the Act and qualification requirements of all applicable state securities laws.

     5.3   Authorizations. All authorizations, approvals or permits, if any, of
any governmental authority or regulatory body that are required in connection
with the lawful issuance and sale of the Stock pursuant to this Agreement shall
have been duly obtained and shall be effective on and as of the Closing.

     5.4   Initial Public Offering of Series B Common Stock. The closing of the
initial public offering of the Company's Series B Common Stock shall have
occurred.

     5.5   Payment of Purchase Price. The Investor shall have delivered to the
Company the purchase price for the Stock as set forth in Section 1.2 hereof.

6.   Covenants of the Company and the Investor.

     6.1   Agreement Not to Transfer.

     (a)   Prior to 180 days after the Closing, the Investor shall not, directly
or indirectly, Transfer or offer to Transfer any shares of the Stock other than
to Affiliates who agree to be bound by the terms of this Agreement, unless the
Company consents to such Transfer and the transferee agrees to be bound by this
Agreement.  For purposes of this Agreement, the term "Affiliate" shall mean,
with respect to a person or entity, any person or entity controlling, controlled
by or under common control with such person or entity.

     (b)   In order to enforce the transfer restrictions set forth in this
Section 6, the Company may impose stop transfer instructions with respect to the
shares of Stock until the end of the restricted period.

     (c)   As used in this Agreement, the term "Transfer" shall mean any sale,
transfer, assignment, hypothecation, encumbrance or other disposition, whether
voluntary or involuntary, of shares of the Stock. In the case of a
hypothecation, the Transfer shall be deemed to occur both at the time of the
initial pledge and at any pledgee's sale or a sale by any secured creditor or a
retention by thc secured creditor of the pledged shares of the Stock in complete
or partial satisfaction of the indebtedness for which the shares of the Stock
are security.

     6.2   Market Stand-Off. In addition to the transfer restrictions set forth
in Section 6.1 above (which shall in no way be limited by the following), in
connection with any underwritten public offering by the Company of its equity
securities pursuant to an effective registration statement filed under the Act,
the Investor shall not Transfer or offer to Transfer any shares of the Stock
without the prior written consent of the Company and its underwriters. Such
restriction (the "Market Stand-off") shall be in effect for such period of time
from and after the effective date of the final prospectus for the offering as
may be requested by the Company or such underwriters; provided, however, that
(i) such Market Stand-off shall not exceed one hundred eighty (180) days, and
(ii) the Investor shall be subject to the Market Stand-off only if the officers
and directors of the Company are also subject to similar restrictions. In order
to enforce the Market Stand-off, the Company may impose stop-transfer
instructions with respect to the Stock until the end of the applicable stand-off
period.

     6.3   Notice of Intention to Transfer. In the event the Investor plans to
Transfer shares of the Stock in one or more transactions, the Investor shall
inform the Company of such intention to Transfer

                                       4
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such shares five (5) days prior to such Transfer. Investor shall agree that any
transfer, sale or other disposition of the Company's Common Stock shall be
through an orderly disposition, including, at the request of the Company,
through a broker-dealer recommended by the Company.

     6.4   Registration of Stock. The Company agrees that, with regard to the
Stock, the Investor shall become subject to the Amended and Restated Investors
Rights Agreement attached as Exhibit A (the "Rights Agreement") for the sole
purpose of providing the Investor with the demand, piggyback and Form S-3
registration rights described in Sections 2.2, 2.3 and 2.4 of the Rights
Agreement.  Solely in connection with such demand, piggyback and S-3
registration rights set forth in Sections 2.2, 2.3 and 2.4, the Investor shall
be deemed to be a "Demand Holder" as defined in Section 1.1 of the Rights
Agreement and the shares of Series B common stock held by the Investor shall be
deemed to be "Demand Shares" and "Registrable Securities" as such terms are
defined in the Rights Agreement.

     The Investor understands and agrees that (i) the Stock will be
characterized as "restricted securities" under the federal securities laws
inasmuch as it is being acquired from the Company in a transaction not involving
a public offering and that under such laws and applicable regulations such
securities may be resold without registration under the Act only in certain
limited circumstances, and (ii) each certificate representing the Stock and any
other securities issued in respect of the Stock upon any stock split, stock
dividend, recapitalization, merger or similar event (unless no longer required
in the opinion of counsel for the Company) shall be stamped or otherwise
imprinted with appropriate legends mandated by federal and state securities
laws.

     6.5   Publicity.  Except as required by law, no press release, public
statement, advertisement or similar publicity from any party hereunder with
respect to the participation of the Investor in the transactions contemplated
hereby (or any other matter relating to the Company and the Investor or its
affiliates) shall be issued or made without the prior consent of Investor.
Notwithstanding the foregoing, the Company may disclose Investor's investment in
the Company and the terms thereof and such other information previously approved
by Investor as of the date hereof for inclusion in the Registration Statement.

7.   Miscellaneous.

     7.1   Governing Law. This Agreement shall be governed in all respects by
the laws of the State of Colorado as applied to agreements among Colorado
residents entered into and to be performed entirely within Colorado, without
regard to the conflict of law provisions thereof.

     7.2   Survival; Additional Securities. The representations and warranties
set forth in Sections 2 and 3 shall survive the execution and delivery of this
Agreement and the Closing until the applicable statute of limitation, upon which
a claim is brought, expires.  The covenants and agreements set forth in Section
6 shall survive in accordance with their terms. Any new, substituted or
additional securities which are by reason of any stock split, stock dividend,
recapitalization or reorganization distributed with respect to the Stock ("Stock
Distributions") shall be immediately subject to the covenants and agreements set
forth in Section 6 to the same extent the Stock is at such time covered by such
provisions.

     7.3   Successors and Assigns. Except as otherwise expressly provided
herein, the provisions hereof shall inure to the benefit of, and be binding
upon, the respective successors and assigns of the parties hereto. Nothing in
this Agreement, express or implied, is intended to confer upon any party other
than the parties hereto or their respective successors and assigns any rights,
remedies, obligations, or liabilities under or by reason of this Agreement,
except as expressly provided in this Agreement.

                                       5
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Notwithstanding anything to the contrary contained herein, the covenants set
forth in Section 6 shall not be binding upon any entity (other than an affiliate
of the Investor) which acquires any shares of the Stock or a Stock Distribution
in a transaction permitted hereunder.

     7.4   Entire Agreement. This Agreement constitutes the entire understanding
and agreement between the parties with regard to the subject matter hereof.

     7.5   Notices.  Except as otherwise provided, all notices and other
communications required or permitted hereunder shall be in writing, shall be
effective when given, and shall in any event be deemed to be given upon receipt
or, if earlier, (i) five (5) days after deposit with the U.S. postal service or
other applicable postal service, if delivered by first class mail, postage
prepaid, (ii) upon delivery, if delivered by hand, (iii) one (1) business day
after the day of deposit with Federal Express or similar overnight courier,
freight prepaid, if delivered by overnight courier or (iv) one (1) business day
after the day of facsimile transmission, if delivered by facsimile transmission
with copy by first class mail, postage prepaid, and shall be addressed, (a) if
to the Investor, at the Investor's address set forth below its signature, or at
such other address as the Investor shall have furnished to the Company in
writing, or (b) if to the Company, at its address as set forth below its
signature, or at such other address as the Company shall have furnished to the
Investor in writing.

     7.6   Amendments and Waivers. Any term of this Agreement may be amended and
the observance of any term of the Agreement may be waived (either generally or
in a particular instance and either retroactively or prospectively) only with
the written consent of the Company and the Investor.

     7.7   Legal Fees. In the event of any action at law, suit in equity or
arbitration proceeding in relation to this Agreement or the Stock or any Stock
Distribution, the prevailing party shall be paid by the other party a reasonable
sum for the attorneys' fees and expenses incurred by such prevailing party.

     7.8   Expenses. Irrespective of whether the Closing is effected, the
Company and the Investor shall each pay their own costs and expenses incurred
with respect to the negotiation, execution, delivery and performance of this
Agreement.

     7.9   Titles and Subtitles. The titles of the paragraphs and subparagraphs
of this Agreement are for convenience of reference only and are not to be
considered in construing this Agreement.

     7.10  Counterparts. This Agreement may be executed in counterparts, each of
which shall be an original, but all of which together shall constitute one
instrument.

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

     7.12  Confidentiality. The parties hereto agree that, except with the prior
written permission of the other party, it shall at all times keep confidential
and not divulge, furnish, or make accessible to anyone any confidential
information, knowledge, or data concerning or relating to the business or
financial affairs of such other party to which said party has been or shall
become privy by reason of this Agreement, discussions or negotiations relating
to this Agreement or the performance of its obligations hereunder.

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     7.13  Termination. In the event that the Registration Statement relating to
the initial public offering of the Company's Series B Common Stock shall not
have been declared effective on or before May 12, 2000, then as of such date
Investor may, at its option, terminate this Agreement and upon such termination
this Agreement shall be of no further force or effect, and neither party shall
have any liability hereunder.

     IN WITNESS WHEREOF, the parties hereto have caused their duly authorized
officers to execute and deliver this Agreement as of the date first above
written.


                              FIRSTWORLD COMMUNICATIONS, INC.



                              By:    /s/ Sheldon S. Ohringer
                                 -------------------------------------------
                              Name:  Sheldon S. Ohringer
                                   -----------------------------------------
                              Title: President and Chief Executive Officer
                                    ----------------------------------------


                              SAIC VENTURE CAPITAL CORPORATION



                              By:    /s/ Ira J. Miller
                                 -------------------------------------------
                              Name:  Ira J. Miller
                                   -----------------------------------------
                              Title: President and Treasurer
                                    ----------------------------------------


                                       7
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                                   EXHIBIT A
                                   ---------

[FirstWorld Communications, Inc. Amended and Restated Investor Rights Agreement,
    First Amendment to Amended and Restated Investor Rights Agreement, and
      Second Amendment to Amended and Restated Investor Rights Agreement]

                                      A-1