[KarmaKiller]

Newegg.com - AMD Athlon X2 7550 Kuma 2.5GHz 2 x 512KB L2 Cache 2MB L3 Cache Socket AM2+ 95W Dual-Core Processor - Processors - Desktops
$50

Newegg.com - ASUS M4A78 Plus AM3/AM2+/AM2 AMD 770 ATX AMD Motherboard - AMD Motherboards
$80 ($70 after MIR)

Newegg.com - G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit Desktop Memory Model F2-8500CL5D-4GBPK - Desktop Memory
$55 (free shipping)

Newegg.com - ASUS EN9600GSO/DI/512M GeForce 9600 GSO 512MB 192-bit GDDR3 PCI Express 2.0 x16 HDCP Ready Video Card - Desktop Graphics / Video Cards
$70 ($55 after MIR)

Newegg.com - Rosewill R223-P-BK 120mm Fan ATX Mid Tower Computer Case - Computer Cases
$30 free shipping

Newegg.com - Western Digital Caviar SE WD2500AAJS 250GB 7200 RPM 8MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive - Internal Hard Drives
$48

Newegg.com - SAMSUNG Black 22X DVD+R 8X DVD+RW 16X DVD+R DL 22X DVD-R 6X DVD-RW 12X DVD-RAM 16X DVD-ROM 48X CD-R 32X CD-RW 48X CD-ROM 2MB Cache SATA 22X DVD Burner - CD / DVD Burners
$25


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Total: $358 (assuming you still have the PSU and a OS)

How's that?