I've found this neat program called DeskScapes, and what it does is enable you to install moving backgrounds for your desktop, which are basically encoded MPEG video files in a .dream format (therefore rather low CPU use), which looks really neat, especially in 3D. The official website is
here. It is usable for nearly all OS, however it's only free for Vista Ultimate... that is, if you you download from the official site.
There is a workaround solution involving an older version of the software, but is not entirely legal (torrent), therefore I won't post it here. But I am willing to send a PM for those who ask.
Oh and here's a list of dream files
here and YouTube examples
here.