Windows 7 has a nice feature that will change your desktop background every 30 minutes (configurable). When setting up a new Windows 7 computer my first item of business is to select a theme. Right click and select “Personalization” to choose a theme. Then on the Personalization window you can click “Desktop Background on the bottom and it will show you the pictures that are a part of the theme. From here you can choose the pictures that show up as part of the theme and tell windows where to look for more pictures. I’ve been putting new photos directly in the United States them folder at C:\Windows\Globalization\MCT\MCT-US\Wallpaper. The best site I’ve found for getting desktop images is www.caedes.net. Caedes is sort of a YouTube for desktop background (all user created content). Recently I’ve discovered another nice site at http://www.shiftedreality.com/, this is all one person’s work, some photography, some rendered, all very nice.