Windows 7 includes variety of wallpapers and themes for you to choose on the Personalize window. However, there’s a much wider variety of international themes and wallpapers that you can add to the Windows 7 desktop. Only your own regional theme is included on the Personalize window, but you can still open the rest.
To do so, copy the following with Ctrl + C: C:\Windows\Globalization\MCT. Then paste that (Ctrl + V) into the Window 7 search box on the Start menu. Alternatively, you can also paste that location in the Windows Explorer location bar and press Return. That should open the following Windows Explorer page.
What you then have is a number of folders full of additional wallpapers and themes! Click on a folder such as MCT-FR, and select France (or any of the alternative regions it includes). That should open a window with a few regionally themed wallpapers as in the shot below.
Then right-click any of the wallpaper thumbnails, and click Set as desktop background. That adds the thumbnail wallpaper to your desktop as below. Alternatively, click Preview from the context menu to expand the wallpaper first.
That is the new Windows 7 desktop wallpaper. To add a new theme, click on the regional theme subfolder. Then click on the theme to add it to your desktop. The Windows 7 theme window should also open with the new regional theme included among My Themes.
You can also find the secret wallpapers with the Windows 7 Logon Background Changer software. This is software that you can change the Windows 7 logon background with. Note that it includes all regional wallpaper with its default Windows 7 thumbnails.
The C:\Windows\Globalization\MCT location gives you access to a whole new range of secret Windows 7 desktop wallpaper and themes that were not initially on the Personalize window. Consequently, you can customize the desktop with a much greater variety of wallpapers and themes already available on Windows 7.