Newegg.com - Intel Core 2 Quad Q6600 Kentsfield 2.4GHz 2 x 4MB L2 Cache LGA 775 Quad-Core Processor - CPUs / Processors
$220
Newegg.com - PC Power & Cooling S610EPS EPS12V 610W Continuous @ 40°C Power Supply 100 - 240 V UL, cUL, CE, CB, TUV - Power Supplies
$110
Newegg.com - Seagate Barracuda 7200.11 ST3500320AS 500GB 7200 RPM 32MB Cache SATA 3.0Gb/s Hard Drive - Internal Hard Drives
$100
Newegg.com - G.SKILL 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory - Desktop Memory
$44
$475-$500 so far...
mobo,card, and case are all up to you...depends what you want to do...maybe change RAM around if you want
Nice build but I recommend this HDD instead
Newegg.com - Western Digital Caviar SE16 WD6400AAKS 640GB 7200 RPM 16MB Cache SATA 3.0Gb/s Hard Drive - Internal Hard Drives