Decided to do a quick rough build for you, came out cheaper then what you currently have and is a lot more well rounded IMO.
https://secure.newegg.com/WishList/MySavedWishDetail.aspx?ID=9566125SAMSUNG 22X DVD±R DVD Burner with LightScribe Black SATA Model SH-S223Q - OEM
Antec Nine Hundred Black Steel ATX Mid Tower Computer Case - Retail
Seagate ST3640323AS 640GB 7200 RPM SATA 3.0Gb/s Hard Drive - OEM
EVGA 512-P3-1150-TR GeForce GTS 250 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card - Retail
PC Power & Cooling S75CF 750W EPS12V SLI NVIDIA SLI Certified (Dual 8800 GTX and below) CrossFire Ready 80 PLUS Certified Active PFC Power Supply - Retail
OCZ Vista Upgrade 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model OCZ2VU8004GK - Retail
EVGA 122-YW-E173-TR LGA 775 NVIDIA nForce 750i SLI ATX Intel Motherboard - Retail
Intel Core 2 Duo E8400 Wolfdale 3.0GHz LGA 775 65W Dual-Core Processor Model BX80570E8400 - Retail
Microsoft Windows XP Professional SP2C 64-bit for System Builders - OEM
Total = $893