You'll probably need to do at least a repair install:
http://support.microsoft.com/default.aspx?scid=kb;en-us;315341
"How to Perform an In-Place Upgrade (Reinstallation) of Windows XP"
(In brief: change the BIOS settings to boot from the CD drive. Boot from the
XP CD. Choose to install rather than going to the repair console. Under
install, choose repair rather than new.
You will have to activate XP again. You may be able to do it over the Net,
depending on when it was last activated. The worst case is that you'll have
to do it by telephone, explaining the mainboard upgrade.
The above applies if you have a retail XP CD. It may not be possible if you
have an OEM version, or a manufacturer's restoration disk. I'm not familiar
with the variety of discounted versions.
HTH.
Bob Knowlden
Address may be altered to avoid spam. Replace nkbob with bobkn.
