PSU: Enermax 495, OCZ Powerstream 420 or OCZ Modstream 450 are nice. If you want to save some money and get a good one still, Tagan 480 is excellent.
CPU: I'd drop to A64 3000+ or 3200+ and overclock. This will save you a lot of money.
Motherboard: You can add $30 and get DFI LanParty Nforce 4 Ultra-D for $160 or find the Chaintech board cheaper for $100 (on newegg?)
Videocard: For $280 you can get X800XL which is just as fast as 6800GT. Sure GT has SM3.0 and overclocks to Ultra speeds but you are paying $200 MORE for it !!! That is ridiculous given New generations cards are going to come out this summer and your card's value will drop from $500 instead of $280.
X800XL vs. 6800GT
X800XL vs. 6800GT - review 2
Also get NEC3520 DVD burner or LG-4163.
I dont recommend SLI. If you think you'll benefit from its upgrade path then get
6800GT PCIe for $378 for now
With RAM, go with CorsairValue, KingstonValue or
Kingmax 1 gig - $73 (MIR)You can just use dividers when overclocking. Everything else is overkill
Now if you combine these savings, in 6 months you'll be able to upgrade to a faster cpu or videocard.