Barbel,
What has happened here is that you have incorrectly set up the Faderport.
The Faderport utilizes MiDi over USB and would need to be setup accordingly. The way you have it currently setup, has the FP routing from USB AUDIO and then send to Firestudio. As the FireStudio utilized the 5-Pin Midi, this would not be a proper way to route the FP.
Proper Setup: Receive From should be USB, as well as the Send To should be USB.
-XP sees the Faderport as a " USB Audio Device" and will not show it labeled as a Faderport. Newer OS's will show it as a Faderport, however.