Hi!
Thanks for your answer.
Well, I kept looking further and I found some information.
It seems, as if the XBOX controllers are just USB with different connectors (see
here!).
Therefore it is obviously very easy to "create" a special USB cable to connect an XBOX game controller to a standard computer via USB.
Of course, there are already prepared adapter cables, which are even not very expensive (see
here or
here!).
Strangely, it seems as if the drivers for the adapter cable support only Windows 2000 or XP.
But I have found a website with some other drivers (
XBCD - XBox Controller Driver) which actually do support Windows 98 as well.
I think, I will just give it a try.
If it doesn't work, my brother will be able to use the adapter cable with an XBOX game controller, because he has Windows XP.
I will let you know in a few days, whether it works fine.
Greetings, DotWin!