ASUS M2R32-MVP ATX AM2 Xpress 3200 Crossfire 2PCI-E16 2PCI-E1 2PCI SATA2 1394 GBLAN Motherboard
$141.45

AMD Athlon 64 X2 4000+ Dual Core Processor Socket AM2 Brisbane 2.1GHZ 2X512KB 65NM 65W Retail Box
$87.45

Corsair Value Select PC2-5300 2X1GB DDR2-667 240PIN Dual Channel Memory Kit
$102.71

ASUS GeForce 7600GS 400MHZ PCI-E 256MB 128BIT 800MHZ DDR2 VGA DVI-I HDTV Out Video Card
$101.98

...and possibly add if existing 350W power supply won't cut it:

Thermaltake TR2 W0070 430W ATX12V V1.3 24PIN/20PIN Power Supply Dual 80MM Fan /W 6PIN PCI-E
$45.15