Once you are in the WAV domain.....tinkering around with sounds becomes more tricky.
My advice is to keep things in the MIDI domain for as long as possible. Sequence them using cubasis until everything is how you want it. Make sure every part is on a seperate track (even parts of the same MIDI channel) then record the whole part to WAV for sound manipulation. Then track them in cubasis (although you are limited to only 8 parts).
Another option that might appeal is to use sound fonts which is an option provided by the Audigy. This basically works like a simple sampler for your soundcard where samples can be loaded into and played back. however, you will not be able to use the
synthisis of the xp to change the sound.
Hope this helps!!!!!!!!!!