SATA is just faster than firewire or USB2. It's major drawback is that not many people use it externally so it's not as universal as USB or firewire. The Mac Pro has 6 total SATA ports, but someone else will have to say for sure if they support hardware RAID (I'm thinking that it's an Intel chipset, then the capacity must be there for at least Intel Matrix RAID but I really don't know).