I haven't had any experience with XP, but I run Windows 2000 at work and home and I can run both games on there fine. And Win2000 is a NT based operating system.
Hopefully someone that knows XP can give you some advice.
I was going to move this to Oddworld Help, but something messed up and I can't move it anymore.
Abe Babe...
[ January 30, 2002: Message edited by: Abe Babe ]