If you wanted access to all the themes that are in Windows 7 all you do is hit the Windows button and in the search box just enter:
C:\Windows\Globalization\MCT... and hit ENTER.
Now you'll see a load of folders like below:
Each folder represents a different Country, AU for Australia, CA for Canada, GB for Great Britain, US for the United States, and ZA for South Africa and so on.
To install the theme for any of the countries, just go into the relevant folder, for example MCT-AU (Australia) and then into it's respective 'Theme' folder and double-click 'AU.theme'. Do this for any of the other folders and you'll see your theme change