Hi Karen,
Yes. Project 2000 can read project 2003 files. From Help:
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The file format of Microsoft Office Project 2003, Microsoft Project 2000,
and Microsoft Project 2002 are the same.
In Microsoft Project 2000 and Microsoft Project 2002, you can open a project
created in Microsoft Office Project 2003 and save it with any changes you
make, and then open it again in Microsoft Office Project 2003. Note, however,
that Microsoft Project 2000 and Microsoft Project 2002 do not include all of
the features found in Microsoft Office Project 2003. Therefore, some
information might not be displayed when you open a project created in
Microsoft Office Project 2003 in Microsoft Project 2000 or Microsoft Project
2002.
When you reopen the project in Microsoft Office Project 2003, all
information will be displayed again. The project will retain all of the
Microsoft Project 2000 or Microsoft Project 2002 information as long as you
don't save the project with a new name. When you save the project with a
different name, all Microsoft Project 2000 and Microsoft Project 2002 items
are discarded.