I've tried to re-install windows on top of pre-existing XP
professional.

After setup, I get the error message "Windows XP Setup
cannot run under Safe Mode. Setup will restart now."  If I
boot from Windows XP setup disc, it will state that
Windows is trying to upgrade already.  If I continue
upgrade, it will copy all the files again and reboot, only
to have the same error message: "Windows XP Setup cannot
run under Safe Mode. Setup will restart now" after startup.

Any ideas?  I would like to avoid doing a clean install
due to the files I need.  Is it still possible to keep my
existing documents/files if I do a clean install?

Thanks,
Dinkoh