Yup, a GTX 260 would be good along with the OCZ 500W PSU I posted up earlier.
ok... let me repost the current specs and costs that i have...
-G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Desktop Memory Model F2-8500CL5D-4GBPQ - $49.99
-Seagate Barracuda 7200.12 ST31000528AS 1TB 7200 RPM SATA 3.0Gb/s 3.5" Internal Hard Drive - $99.99
-ZOTAC ZT-X26E3KD-FSP GeForce GTX 260 896MB 448-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card - $144.99 after $25.00 Mail-In Rebate
-Antec Three Hundred Black Steel ATX Mid Tower Computer Case - $58.95
-ASUS M4A78 Plus AM3/AM2+/AM2 AMD 770 ATX AMD Motherboard - $79.99 (+ 8 for shipping)
-Rosewill RP550V2-D-SL 550W ATX12V v2.01 SLI Ready CrossFire Ready Power Supply - $54.99
-AMD Phenom II X4 940 Deneb 3.0GHz Socket AM2+ 125W Quad-Core Black Edition Processor Model HDZ940XCGIBOX - $189.99
-SAMSUNG 22X DVD Burner Black SATA Model SH-S223F - $24.99
Subtotal: $740.51 + 150ish for speakers, keyboard + mouse, and monitor
Grand Total ~ $890 ($11.63 Shipping for mobo and gpu)