If I were I would get 8800GTS 320MB
Newegg.com - EVGA 320-P2-N811-AR GeForce 8800GTS 320MB 320-bit GDDR3 PCI Express x16 HDCP Video Card - Retail
Newegg.com - EVGA 320-P2-N811-AR GeForce 8800GTS 320MB 320-bit GDDR3 PCI Express x16 HDCP Video Card - Retail