This site is extraordinary with several flyovers of the planet Mars and visuals suitable for wallpaper and screen savers:
You will need the DivX player and there is a free version:
You have to right click the download at the site and "Save target as" to download the movie to your hard drive -- I'd go with putting the icon on your desktop.
If you try to watch or download, the Windows Media Player or whatever your default player will attempt to play it and doesn't have the DivX codec. I haven't tried Quicktime or Real Player which may have the codex. Right click on the icon on your desktop and check "Open with," scroll down to the DivX player and click. Otherwise, it will still try to play it with Windows Media. The next time you click on "Open with," the DivX player will appear on the tree.