Silverstone Stride 600W (if you want modular cabling)
Corsair HX620W (also modular)
All three are great power supplies, if price is the most important issue get the Strider, if you feel you want a little extra power the Corsair is also modular but delivers 50A instead of 42A. The Olympia delivers the most power and is cheaper than the Corsair, but its not modular. Any of the three will power you system perfectly fine.
but because i have to say this is if your on a budget don't bother with a RAID0 setup with 74GB raptors. The extra performance you get won't be nearly worth the money. If your dead set on RAID0 get two Seagate 250GB or something a little smaller. If your dead set on a raptor drive get one 74GB Raptor and one Seagte 250GB. Either way you'll save quite a bit of money and have nearly the same performance.
Your real life wattage would probably be under 400 watts. My E6600 is less powerful than the Q6600 but with four harddrives and the 8800GTS I am only measuring 220 watts AC under load. It's not bad to have a lot more power than you use, but you said you are on a budget, so that's something to consider.
The question is not wattage, but how many amps can be delivered at 12v. This is a function of the efficiency of the PSU and how many watts go to the 12v side vs. the rest. Nvidia recommends 26A on the 12v rails for a 8800gts. Check out this psu reference list for a list of quality units: http://forumz.tomshardware.com/hardware/modules.php?nam... Look for a psu that has at least 26amps, and that does not have an asterisk in front which indicates that it is not suitable for a Quad core cpu. About the lowest priced unit I see on the list is an Antec NeoHe 430w for $70. You can get this psu included in an Antec P150 case for $139 delivered. Otherwise, I would look at a Seasonic unit, if for no other reason that they make several of the psu's sold under other brand names.
On the Hard drive, consider getting a single 150gb raptor. It will cost you $170 vs. $270 for the two 74gb units. The performance will actually be better. Go to www.storagereview.com for a thorough tutorial on raid-0 and some benchmarks that are representative of what a single user in a desktop environment might expect. Synthetic benchmarks like hdtach are accurate enough, but are misleading as a predictor of value to you. On other benchmarks, look at the values where the queue level is 1, or 2 at most.