To install a different language - Multilingual User Interface (MUI) - you need to have Windows 7 Ultimate.
Anytime Upgrade to Windows 7 Ultimate
Type Anytime Upgrade in the Search programs and files box in the Start
menu and click on the Windows Anytime Upgrade icon. From there, you can
buy an Anytime Upgrade to Windows 7 Ultimate. Then your can enter your
Anytime Upgrade product key and perform a
simple upgrade to Windows 7 Ultimate so you can install a different
If you are in Australia, Belgium, Canada, France, Germany, Italy, Japan,
the Netherlands, Spain, Sweden, Switzerland, the UK, and the US you can
use Anytime Upgrade. If not you will need to buy Windows 7 Ultimate, or
buy Windows 7 in the language you need.
Install Language Pack in Windows 7 Ultimate
1. Start -> All Programs --> Windows Update --> Optional Updates.
2. Open optional Updates and go to the section Windows 7 Language Packs.
3. Tick the Language Pack you want and hit OK
4. Proceed with Install Updates
5. Depiction of Windows 7 downloading a Language Pack
6. Automatic install initiated after download
How to change the Windows 7 Display Language:
1. Go to Start -> Control Panel -> Clock, Language, and Region / Change the display language
2. Switch the display language in the Choose a display language dropdown menu.
3. Click OK
4. Log off for the changes to take effect (This will affect only the user profile under which you are currently logged on).