Windows 7 has many hidden themes in it. It provides location specific themes to users. Users get access to themes according to the information provided at the time of installation.It has 5 different set of themes for different countries.
To access those hidden themes for other countries you will have to unhide the hidden system files and folders. To do this open My computer. Click on Organize -> Folder and Search Options -> view tab. Now navigate to C:\Windows\Globalization\MCT.
There you can see five different folders each for five different countries US, Canada, South Africa, Britain and Austrailia.Open any of the folder and there go inside the theme folder. Double click on the theme file to activate that theme.
Don’t forget to hide your protected system files again.
Enjoy your new themes.