I was browsing on my lunch break just a little while ago, and found what I consider a more interesting motherboard. I've heard of a few problems with the ASUS P5 boards, especially regarding RAM and BIOS limitations. I was browsing newegg, not toms, though. Prices may vary.
HIS Radeon 512MB HD 2600XT: $150
ASRock 4Core1333_eSata2 R5.0 (what I love about ASrock is they support ALL FSBs from 533 to 1333 on this board! perfect for later upgrading!! Also good for overclocking) $90
Conroe E6550 1333MHz FSB 2.33GHz $170 (overclockable out the wazoo)
Those 3 instead of your mobo/CPU/GPU will save you $70 and I don't see any loss in performance, really. The HD 2600XT is a competitor for the 320MG Ge8800GTS, so it'll be considerably better than the Ge8600, so that's a boost in performance.
My opinion: With the ample muscle of even the lowest 1333 FSB Conroe, I don't see buying the "higher" rated ones because I see it this way: 1) nothing's going to bog this down for 3 years, and 2) if anything comes close to bogging it down, I just overclock it 160% and it doesn't bat an eyelash. Given that philosophy, I'd go for the lowest "acceptable" chip that leaves you the option of upgrading in the futures (anything in the Socket775, 1333 or 1066 FSB range, and a motherboard that has Socket775 and supports 1333 or higher FSB). This will save you some $$$ for other components, or even for your pocketbook.