I have been using WinXP since beta 1 and haven't had any problems with software compatability, hardware is another matter. Before you do the upgrade, check with all of your hardware vendors (printers, scanners, fax, video card,etc ...) just to make sure they have XP drivers. XP doesn't come with drivers for everything. Now as far as the upgrade goes, it is best and you'll have fewer problems if you do a clean install of XP on a fdisk'd drive. Also under XP you can use NTFS, XP has better memory management than Win9x did. I have had Rhino and Bryce5 as well as Bryce5 and Poser4 open at the same time under Xp and haven't had any trouble with crashes.