There was a patch for windows XP systems running on dual core processors. I had this problem with my Dell laptop and couldn't figure out why the hell my superfast system was running a 7 year old game like it was SETI.
Here's the link:
http://support.microsoft.com/kb/896256
Standard Disclaimer: Do all of the registry back up shit, etc. that you would with any OS patch. If it botches install, call Richmond, WA... not me.
Dax