Ok I have an XFI Xtreme Gamer sound card and Medusa 5.1 8790 Heatset, and I dont get any sound out of my rear right speaker! In the creative test it just doesnt play any sound, whereas in CS:S rear right sound is play quietly in the rear left speaker! But if I plug speakers straight into the sound card it works fine; therefore its the drivers and medusa amp having probs with each other. Does anyone know how to fix this? I have the lastest drivers for XP (Oct 06). Starting to think that I want my old Audigy 2 back that I sold 
