Funny you should ask about hard drive speed and benefits raptor vs standard sata ..... I just went through all that myself, Here is what I have found to be a much better hard drive solution than the raptor/velociraptor (cant be sure about the latter one but from the looks of things I would say my solution is still better) or ssd hard drives. First of all of course the ssd hdd's would definately be the best solution but who can really afford those if you can more power to ya send me a few lol. Now the solution I have been raving about is three little letters S.A.S. two of these drives paired with a moderatly priced controller in raid 0 is faster than four thats right four raptors in raid 0 on an onboard controller. Thats it no complaining no whining about raptors they are not the end all and be all. That being said I will tell you my setup wich consists of (lsi megaraid 8704elp, and four fujitsu 73gigers at 15000 rpm) I have attached three benchmarks and as you can see the throughput on the sas setup is far better than any raptor raid 0 that can be set up on an onboard controller. Unless you have six of them raid 0ed together and I still doubt that would beat my numbers simply because of the limitation of the onboard raid controller. As you can see from the attachment with four drives running there is still a bottleneck on my system ( you can tell this from the mostly flat line from start to finish note its not as noticable with only two) I am attributing this to my motherboard wich is currently the 680I, although thats only my guess could be the sas controller I bought but I doubt it. Now as far as money goes here is the comparison.
4 74gig Raptors controlled by onboard will cost you $559.96
1 lsi megaraid 8704elp $325
2 73gig fujitsu drives $372 for a grand total of $697
and of course just add $372 for the four drive setup
Now yes my way is more expensive but hey you want more speed right, its not free, and from the looks of your new system you aren't exactly totally concerned with penny pinching. Thats it compare the hd tachs and that will give you all the info you need to figure out what best suits your setup. Hope this helps ya.
attachments from left to right are four raptors on 680i onboard controller, four sas drives on 8704, and then two drives on 8704. All are on the 680i