I switched from ME (NEVER had a problem), and have had XP Pro (Full Version, not Upgrade).  I love it and still do not have a problem.  800Mhz PIII, 394Mb SDRAM, Hercules GeForce DDR-DVI (32Mb) [75 fps, 40 in a furball], XP Pro.  I agree with the above posts.  I personally do NOT like 98SE, we have it at our work and I have too many problems with it.  HOWEVER, I know alot of people that have it and LOVE it.  
Majority rules here, don't change it.
Karaya2