When I play a DVD movie under Windows XP Professional Edition, the video looks fine, but the audio sounds terrible. I know the DVD is OK because it sounds fine when playing under Windows 2000. I've tried replacing my sound card, but it didn't make any difference. Do you know what's going on?

The problem is likely with your video card, not your sound card. Video adapters not fully compatible with XP can cause problems with audio playback. Try updating your video-card drivers or buying a new card that has XP drivers.