It's been a while since I used it, but you may want to investigate DreamScene. It allows you to set a short .wmv video clip to play as a video-screensaver when idle. When the PC is in use, the video pauses. Obviously, you'll have to get creative and come up with background images that will mesh with the music clip you want playing. For a time, I had the Star Trek U.S.S. Enterprise orbiting Earth with the impulse engines humming through the speakers.