yessssssssssssss!

Stephen, you're the greatest!

Though I didn't know what to do in the directories you pointed me to, I just put these into my XF86Config-4 file, restarted my X server an voila: It works!

And not only that you have solved the problem with the fonts, after doing what you said, I was able to run netcardconfig and now I've got a running network connection in debian!

yesssssssssssss!

For all who might have the same problem as me, here's my new XF86Config-4 file (the part that I changed):

Section "Files"
# FontPath "unix/:7100" # local font server
FontPath "/usr/X11R6/lib/X11/fonts/local"
FontPath "/usr/X11R6/lib/X11/fonts/misc"
# if the local font server has problems, we can fall back on these
FontPath "/usr/share/fonts/ttf"
FontPath "/usr/share/fonts/truetype"
FontPath "/usr/X11R6/lib/X11/fonts/CID"
FontPath "/usr/X11R6/lib/X11/fonts/Speedo"
# FontPath "/usr/lib/X11/fonts/misc"
FontPath "/usr/X11R6/lib/X11/fonts/cyrillic"
FontPath "/usr/X11R6/lib/X11/fonts/75dpi"
FontPath "/usr/X11R6/lib/X11/fonts/100dpi"
FontPath "/usr/X11R6/lib/X11/fonts/Type1"
EndSection

Thanks again, Stephen!

Timo