Since you have Windows 7 Ultimate
here is what should you do !
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 drop down menu.
3. Click OK
4. Log off for the changes to take effect.
and done ~