Gigashade: HOLY CRAP!!! I just checked Amazon and it's there. Does anyone have first-hand experience of how Planescape:Torment runs on Windows XP?
I don't know if any of the community patches fixed that. But as ceemdee says, it's not a bit different to the CD version. So you might want to try the community patches on your... uh, current copy.
Also note that it might be a video card issue. Yes, it's an old game, but newer drivers sometimes screw things up for older games and it takes them a while to get around to sorting that out. If you haven't already, make sure you've got the latest drivers to be on the safe side.