Okay here it goes. This will give you plenty of power for now and give you good GPU power for the $. If you want to add more GPU, I'd go with the 3870x2 instead of the 8800gts that I listed. It'll cost you about $125 or so more than the GPU listed below, but you can make that decision. I believe the SLI is overatted and thus don't really recommend those setups. There are alot of things that you have to buy to support SLI/Xfire and I believe it's wasted $, but that is just MHO.
CPU - $245!! Getting a G0 OEM CPU!!
Intel Core 2 Quad Q6600 G0 Stepping Kentsfield 2.40GHz 8MB L2 LGA 775 Processor OEM HH80562PH0568M SLACR
http://www.clubit.com/product_deta [...] o=A1938460
Mobo - $130 shipped! One of the better p35 boards available. Get a mobo that has all of the options that you need.
GIGABYTE GA-EP35-DS3R LGA 775 Intel P35 ATX Dynamic Energy Saver Ultra Durable II Intel Motherboard - Retail
http://www.newegg.com/Product/Prod [...] 6813128086
GPU - $277 - $30 MIR = $307!! You can upgrade within 90 days using the "Step Up" program, if you want to get the latest GPU. Limited Lifetime Warranty!
EVGA 512-P3-N841-AR GeForce 8800GTS (G92) 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card - Retail
http://www.newegg.com/Product/Prod [...] 6814130325
PSU - $120 - $20 MIR = $100!!! One of the best PSU's you can get in this price range. Has plenty of connections for your upgrade needs! Has 5 yr. warranty too!
CORSAIR CMPSU-650TX ATX12V / EPS12V 650W Power Supply 100 - 240 V UL, CE, CB, TUV, FCC, CCC - Retail
http://www.newegg.com/Product/Prod [...] 6817139005
Memory - $105 - $15 MIR = $90!! Cheap and fast CAS 4 DDR2. Allows you to upgrade to 8gb's later, if you like.
Patriot Viper 4GB(2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory - Retail
http://www.newegg.com/Product/Prod [...] 6820220293
HD - $100!! You'll enjoy the extra space. If you need more, just buy more now or just buy another HD later.
Western Digital Caviar SE16 WD5000AAKS 500GB 7200 RPM 16MB Cache SATA 3.0Gb/s Hard Drive - OEM
http://www.newegg.com/Product/Prod [...] 6822136073
DVD Burner - $29 shipped!! This is the retail version, so you can view/burn DVD's, because the software is included!
PHILIPS 2-Tone 20X DVD+R 8X DVD+RW 8X DVD+R DL 20X DVD-R 6X DVD-RW 12X DVD-RAM 16X DVD-ROM 48X CD-R 24X CD-RW 48X CD-ROM 2MB Cache SATA 20X DVD±R DVD Burner - Retail
http://www.newegg.com/Product/Prod [...] 6827248008
Case - $120 - $40 MIR = $80!!! One of the best cases in this price range. It cools well and is constructed well.
Antec Nine Hundred Black Steel ATX Mid Tower Computer Case - Retail
http://www.newegg.com/Product/Prod [...] %2bHundred
OS - $100. Probably the best Vista OS for the $.
Microsoft Windows Vista 64-Bit Home Premium for System Builders Single Pack DVD - OEM
http://www.newegg.com/Product/Prod [...] 6832116204
CPU HSF - $23 shipped!! Better deal than the one you listed
Arctic Cooling Freezer 7 Pro CPU Fan For Intel CPU
http://www.ewiz.com/detail.php?name=FAN-AC7PRO
Total ~$1249 - $105 = $1144!! You can obviously find better deals if you go hunting for them, but these are from reputable online vendors, so take that into consideration. Newegg seems to have the best customer service, but doesn't always have a good price on things, so shop around before you purchase. You can decide if any of these will work for you or not, I just wanted to show you what/where you could save some $ on and not really hurt too mucy performance on a single GPU solution.