so far so good. I cant do a repair install because my Windows is German and the downloaded .iso is "english". There is only a professional version of windows 7 in german (but I got ultimate) What to do now? Can I install a professional version "over" the ultimate?
You don't need to do that. Using an Windows 7 Ultimate, means that you could download and install any available language and install, even more that one! let say on English base d installation you could install Germ,an, French, Chines, Thai or what ever Language you like to run! Once the Language is installed, you could change the Layout (Display) Language to any of that installed. It's like you'd natively installed Windows in that language. Personally I would suggest that you do a new and clean installation of the English Windows 7 Ultimate and after that download those other language(s), install and run. I use English an Main and also have Thai and Deutsch installed. Depend in which language I mainly have to do some work, I change to that language, log off and on again and run in that language. Easy to do!