from win2000 to XP - error in conversion - Help!

[J]

Hi

I had Office XP installed on my Win 2000 Pro machine (the
folder says Office10, which I believe was the XP version).
I've since upgraded the O/S to Windows XP Professional.
Now, all of my programs get the same error when I try to
run them.. example: "Microsoft Excel has not been
installed for the current user. Please run setup to
install the application.".
I can't find my cd. Is there a way to fix this?!

Thanks!
J.