First of all: Thanx to Vishal Gupta[link]
for his great tutorial how to do this.
Simply replace the sysdm file in your windows32 folder with this. Rename the original to sysdmbackup before. If you don`t get the Genuine software bmp rename the included bmp to oemlogo.bmp and put it in your system32 folder.
German systemproperties are completely different from english ones. So i don`t think there is another way to do this.
Also included is a little freeware program which allows you to customize the OEM info of your system. If you want to use it, you have to disable your virusprogram or you will come in trouble. With this you can add your own text to the sysprops. Also works on vista.UPDATE: Excluded. If you want this send me a message.
Updated january 18.