I run poser Pro Pack on XP, however my system isn't a typical system from what i've seen people say. I run XP on a 1.3mHz system with 1gig ram, 180gig hd, 64meg vid. Poser runs smooth, and haven't had any problem with it. Some people say XP has alotta problems to it, however I have had yet to experience one of them, guess XP likes me ;). Anyhoo, it runs great for me but im betting it has alot to do with your system. Next step for me is a dual processor system, gotta start saving up.