I can't say anything about Poser 5, but I'd definitely recommend getting a newer OS. It was quite normal for me to reformat and reinstall Windows 98 every 12-18 months or so, but Windows 2000 is one of the best investments I've made for my PC. Everything just works better, and keeps on doing so. XP may be as good, but I haven't felt a pressing need to spend my own money to get whatever advantages it offers; I'm not really sure there are any.