How many graphics cards are you using with how many monitors?
Reason I ask is that if your using two with them in CF/SLI then there going to drop to x16/x8 when you use a PCI-E sound card which if your using a multiple monitor setup may effect the performance, or so I hear.
If you go for the PCI version then you'll keep running at x16/x16.
Just something you may want to consider.
Edit: KoS is right about how we're starting to move away from PCI though so the PCI-E version should last you longer, or at least not limit you as we might see PCI slots on budget boards for some time yet.