Windows 7 offers a good assortment of themes to
customize the feel as well as the look of your computer.
Windows 7 features particular themes which are based on
the location and the language you select while you
install the Windows 7. You can look for the
location-specific theme in the
Personalize menu. You just have to
right-click at any place upon your computer desktop. You
will be able to get the couple of themes according to
your location.

Other than the location specific themes which you get by
default, you can access hidden themes in Windows 7 which
are offered to other regions. So the default themes
which you get according to your region are not the only
themes you can use. It is possible to access hidden
themes in Windows 7 very easily in your system. This is
what you have to do:
Click
Start.
In
the search box of the Start menu, type
C:\Windows\Globalization\MCT.

Your
Windows Explorer will show you a window with additional
themes. These will be from Great Britain, South Africa,
Australia and Canada.

You
have the option to select the wallpaper only or you can
install the whole theme if you want.

You will be able to install the entire brand-new theme
by double clicking on the required file.

The
new theme you add will show under “My
Themes" within the “Personalization"
pane.

You
can also download many themes for Windows 7 from
different website including the Microsoft official
website. But you should first try to customize and
access hidden themes in Windows 7 as you might not feel
the need to download additional themes from elsewhere
after that.