I am one of the unhappy ones.I upgraded about 2 moths ago to SP2 and my pc did some unbelievably crazy things afterwords(auto rebooting,auto defrag ect.) So i assumed my installed version that was on the PC when i bought it was warez(not uncommon at all) so i bought XP/SP2,and although my 3D progs(Vue,Poser,Photoshop and gaming) work better my pc tends to freeze to a necessary restart when rendering at least 3-4 times a week.I know it could be overheating and or voltage issues,but i personally think it is SP2.Otherwise it is good for its security enhancements alone.All ican say is GOOD LUCK,and be prepared for a reformat just in case.