I have an Athlon Xp 1800, Windows Xp with SP1, 1 Gb ram, Abit Siluro video card which uses Nvidia drivers. Motherboard is an Abit KT7A-RAID with Via KT133 chipset. I haven't had any problems. I was using windows 98 with Poser 4 until just a few weeks ago, and used to lock up all the time. Switching to XP fixed that. I built my system, and from lurking around various pc newsgroups video cards which use Nvidia drivers are fairly notorious for causing all sorts of problems, don't know why, since they're so common. I had to put in my 5 year old Diamond video card to get XP to install on my system, and put my AGP card in after it was installed. Poser 5 has slowed down on me and taken a long time to refresh at times, which makes me think it might be a "Poser feeding data to video card" problem that's plaguing so many people, but who knows.