I had a problem on my new build with the GA-EX58 Extreme board, in that with two 4870X2's installed, there was no way I could fit my Creative 2 ZS sound card into the bottom pci-e slot.
So, for not much money, I got the Creative USB external XFi 5.1 jobbie, and it works a treat.
The Audigy went into my nippers machine to do away with his onboard sound.............so everyones happy....