If you need "the driver for medion md9458 scanner for vista", why did you post that you needed it for Windows Server 2003 x64
? I believe you're a bit confused.....
you can check for driver availability on the manufacturers website.
It appears that they only provide drivers for Win 2000/Win 98/Win 98SE/Win ME/Win XP 32bit - dated: 08.08.2003, Version: 1.4.1
File name: sca9458win9xp.exe
File size: 27.8 MB.
I see nothing for either of the OS's you posted.