Do you mean the interface of Office is in Deutsch? or the text that you type in the program (keyboard layout)?
I don't believe the older versions of office supported multiple language UI's meaning that if you bought the Deutsch version of office, you're stuck with it, where as now you can install a MUI pack and get a different localized language version for whatever
locality is available.
If on the other hand it is the text that you're typing and want to change from Deutsch to English keyboard layout, you can use the Regional Settings in the Control Panel to set that.
Hope this helps,
john
John Wildes | Senior Enterprise Architect | United Airlines | Desktop Engineering