How about this for something different?
Animated Triplewide Wallpaper
Enable DreamScenes in Windows 7 here.
http://windows7themes.net/how-to-use-dreamscene-in-windows-7.html
Use Fraps to capture a short clip of a favorite game scene (don't move the character at all, just capture the moving scene, e.g. Assassin's Creed 2 at the Wharf with boats bobbing, or Bad Company 2 with the dust blowing and the trees swaying.
Rename the captured avi to wmv, then rt-click "Set as Desktop Background".
Kind of cool, an "Animated Triplewide Wallpaper" for free. CPU usage was minimal...
For best results, may want to set your resolution lower than typical for best framerate capture.
TIP! Once you have a bit of video, it will loop, to crop the video (rename back to avi) for a better looping end/start point (so a cloud doesn't jump across the sky), you can crop the video to the desired length using VirtualDub (remember to do "Video -> Direct Stream Copy" before saving so it doesn't re-encode the file)...