-1 on the Raptor. Useless. 7200RPMs drives are just as fast now.
Ultra's PSUs are really hit and miss. I cannot find a review on that model. $200 for 800W is high. You can pick up a PC Power and Cooling 750W (not modular for still a good PSU) for $149 or a 1kW Corsair modular PSU for $50 more that is excellent.
Don't buy XP 64-bit.
I would use Patriot RAM. They have a 4GB kit around $80 right now on Newegg.
Motherboard is overkill. Look at the P5E Deluxe instead and save $60 or so.
Read a bit more - Duck was right as always with the 6600 - saving money - getting 6600 - now only to understand how to OC it to say 9x377 for a 3.4 and what RAM. Seems to be more literature on 6600 OC's anyways.
Duck feel free to answer the questions above though .
Gahhh another Asus motherboard. You know, if you really cared about overclocking you'd get a DFI motherboard X38 or X48 Lanparty DK. I'm just teasing of course. But seriously, if you weighed the advantages/disadvantages between those DFI boards and the Asus, then more power to you, if you haven't, you really should.
If you get some DDR2 800, you can be safe all the way up to 1600 fsb at 1:1 without even bothering with raising the clock speeds on the ram.
Get a better heatsink for the cpu and the graphics card. It will pay off, for sure. The surface finish on the AC Freezer 7 Pro was crap when I got it; changed to a Thermalright Ultra 120, and average change in temps was 10C on idle and load. I never use stock cooling on graphics cards, got a VF900 and never see higher than 60c on load with almost silent operation ~8V.