As you maybe expect, it was quite a simple procedure ;D
1. Take the english bootfiles
2. Take your original Setup Disk of Server2003
3. Copy SETUPREG.HIV, SETUPLDR.BIN, NTDETECT.COM and NTDLL.DLL from your setupdisk (in I386\) and paste them to your bootfloppyfiles in the root. Now copy SYSTEM32 directory (also in I386\) to the root of your bootfloppyfiles.
Hummm, I don't know exactly, if this is all you have to do because I copied very much files until it worked. Maybe you have to copy the files:
KSECDD.SYS
NTFS.SYS
SPCMDCON.SYS
from I386\ from setupdisk to the root of the bootfloppyfiles... maybe...
enjoy!