It appears that only Win 7 Ultimate has the language pack capability. The 
MS Anytime Upgrade will allow you to purchase an ugraded version of Win 7 Ultimate. Once Win 7 Ultimate is installed do the follow:
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...