die sprachdateien sind aus:
7600.16385.090713-1255_x64fre_client_langpacks_1-GRMCXLP1_DVD.iso
7600.16385.090713-1255_x86fre_client_langpacks_1-GRMCLP1_DVD.iso
Download X86 DE 
Download X64 DE 
How To:
Start -> Control Panel -> Clock, Language, and Region -> Region an Language -> keyboards and Languages -> bei "Display language" "Install/uninstall languages..." klicken -> *.cab auswählen -> installieren -> reboot