Hi Nancy, I went your way just recently. Poser 4 and Poser 5 (don't have ProPack) work very well with Windows XP Professional. Also other 3D software works very well. There is a problem though. XP is not compatible with the 80-90% of the hardware I have. Including my flatbed scanner, slide scanner, Logitech mouse (yeah), and even the ADSL Modem. I had to make a second active partition and install ME in dual boot just to run the scanners. GO figure. I am using the modem on my other computer which is Win2000 and it's flawless. My advice: forget about WIndows XP. Go Windows 2000 instead. It is: - MUCH faster. This computer with WIn2000 on is almost as fast as my other computer with XP. Only, this is a Pentium 3 800, the other one is a Pentium 4 2.4Ghz... - MUCH more compatible with existing drivers. - Doesn't force you to phone call Microsoft at every reinstall. Cheers, Orio