My Itunes and AppStore are in German, and I can switch them to english
First check Region of your Apple ID:
Open iTunes and click on iTunes Store. In the store, click on Anmelden on the top right and enter your password. Under Apple ID Übersicht select Land oder Region ändern. Choose the appropriate one.

Then check your system locale. You can find it under Systemeinstellungen (System Preferences)->Sprache &amp; Text (Language &amp; Text)->Sprache (Language). Drag English to the top of the list. This will change your system language to English.

If you don't want to, you could use Language Switcher to permanently or temporary to change the language iTunes starts up in. This does not affect the stores!