This appeared on one of the Windows 7 blogs I suscribe to:
1. It’s a Global Village. If you’ve tried to change your desktop wallpaper, you’ve probably noticed that there’s a set of wallpapers there that match the locale you selected when you installed Windows. (If you picked US, you’ll see beautiful views of Crater Lake in Oregon, the Arches National Park, a beach in Hawai’i, etc.) In fact, there are several sets of themed wallpapers installed based on the language you choose, but the others are in a hidden directory. If you’re feeling in an international mood, simply browse to C:\Windows\Globalization\MCT and you’ll see a series of pictures under the Wallpaper directory for each country. Just double-click on the theme file in the Theme directory to display a rotation through all the pictures for that country. (Note that some countries contain a generic set of placeholder art for now.)