Your in luck providing you have Vista Ultimate. Dreamscene will only work with Ultimate edition. Download the Dreamscene of MS *still in build form* Vista DreamScene allows you to choose a video file as a Desktop Background. Once you have downloaded the DreamScene files, you configure the background just as you would for a picture, except you chose a .mpeg instead of a .jpeg. The result is an animated desktop.
Might get out the das boot dvd and have it as my animated desktop