Here's one thought:
Leave your boot drive as the one that came with the machine. It will be in drive bay #1.
If you want screaming performance, set up drive bays 2, 3 and 4 as your Scratch/RAID system. Get three 1TB drives configured via softRAIDto a RAID 5. You can just set PS scratch prefs to the entire RAID volume OR partition the outer portion of the drives into 30GB scratch volumes first, then RAID 5 the rest of the volumes.
Sort of a variation of what Jack Flescher describes here:http://luminous-landscape.com/forum/index....showtopic=36642