If you've managed to upgrade to Vista Ultimate then you just have to checkout the DreamScene feature. Use the Windows Update feature from the start menu and the Windows Ultimate Extras section should offer you the Windows DreamScene application. Download and install it. Then change your wallpaper to Windows DreamScene. It allows you to select a MPEG file as your background. I selected one of the Windows sample videos (butterfly). The effect is stunning. Try it out, even better if you use your own home videos.