Vezi
https://www.youtube.com/watch?v=UIFAMm7Kxn0
sau www.youtube.com/watch?v=5XKUBf_lBqM
sau
You must have Ultimate or Enterprise edition to go from German to English, otherwise you must buy an English version of Windows 7 and re-install the Operating System.
Start -> All Programs --> Windows Update --> Optional Updates.
Open optional Updates and go to the section Windows 7 Language Packs.
Tick the Language Pack you want and hit OK
Proceed with Install Updates
Depiction of Windows 7 downloading a Language Pack
Automatic install initiated after download
How to change the Windows 7 Display Language:
Go to Start -> Control Panel -> Clock, Language, and Region / Change the display language
Switch the display language in the Choose a display language dropdown menu.
Click OK
Log off for the changes to take effect (This will affect only the user profile under which you are currently logged on).