Actually, I just bought the Klipsch Promedia 5.1's with the Creative SB Audigy Xgamer SoundCard and it took me a bit to dial it in but it's a pretty good card. However, my music sounds better running through 4 speakers opposed to Surround 5.1, which is the cards only downfall . Then I heard about the GTXP Hercules on the klipsch forum and I've basically heard that if you go to the hercules website and download the xp drivers, your all set. I've heard that this is the best sound card out there. And I ordered one last week. From what I've heard, this thing plays mp3's,games,DVD's etc... in surround 5.1 with no problems.
The bottom line is that the Santa Cruz is a good card but if you have the extra cash, get the GTXP.
My Creative Xgamer Audigy is a nice card, but in order to get great quality surround 5.1, I have to play my mp3's using Power DVD 4.0 .