Go with the SB95Pv2 if you want the highest peformance box with 4 SATA drive bays plus the optical bay.

Go with the SB86i if you want a quieter solution, but limited to two hard drives.

There is also the SS77G5, though it seems similar to the SB86i.

All 3 offer PCI Express 16x slots for graphics cards. Slap in a good $200ish NVidia 6600 GT and you will have a good little gaming box too. The ATI alternative in that price range is the x700 Pro line, though it tends to be slower then the 6600gt. Sadly ATI gave up ground in the middle of the road market this past time around.

All the above boxes have USB2 and Firewire 400. I haven't seen any Shuttle with Firewire 800 yet.