I just recently got a new computer with Vista. After going through MUCH grief trying to get the first KotOR to work I gave up and concentrated on getting my older XP computer to run again.
The problem was most likely updated drivers, you need to roll back if you want to play NWN I, Kotor I, or Kotor II.
That would suck out loud, as then I'd just have to update again for the newer games. I realllllyy prefer PC over platforms, but moments like this I see why some people like them better. Well for the moment I'll just keep both computers running and use XP for those games. Assuming they will even work on that now. Given that I have just got to the dreaded door for the second time and still have the same problem even with the new series of save games. Not to mention the other little issues I am noting, like the screen blurring into obscurity when using any speed powers or racing. I really do not want to retire these games, and yet they are becoming unplayable.