How to Access Additional Hidden Regional Wallpapers in Windows 7?
METHOD A:
Windows 7 puts all these regional wallpapers in "MCT" folder which is stored under "%windir%\Globalization" folder.
1. First open My Computer and copy-paste following text in addressbar:
%windir%\Globalization\MCT
Press Enter and it'll directly go to "MCT" folder which is actually a hidden folder.
2. You'll see following 5 folders in MCT folder:
MCT-AU MCT-CA MCT-GB MCT-US MCT-ZA

3. Open each folder one by one and you'll see a folder containing the region name in its name under all these 5 folders.
Australia
Canada
United Kingdom
United States
South Africa
Under each region folder, you'll see 6 .jpg files. You just need to copy these .jpg files to anywhere you want and then set them as wallpaper whenever you want.
METHOD B:
You can also use a simple registry script to add all these regional wallpapers automatically in Personalization window. Simply download following ZIP file, extract it and run "Add Additional Regional Wallpapers in Windows 7.REG" file. It'll ask for confirmation, accept it:
Once you run the file, it'll add the additional regional wallpapers in Personalization window:

PS: An uninstallation script is also included in the ZIP file in case you want to remove additional regional wallpapers later.

