you can get a nice open box 8600GT. I bought that exact card, open box and all, for my HTPC and it worked out great. MIR FTL, half the time you end up not getting them.
I built a new rig for one of my cousins just a few days ago for $550 w/o shipping with a 9600GT. Only OC'd the E2160 to 2.4GHz, but the computer is pretty quick and plays everything he wants it to. Had some artic silver and an SATA 80GB HD laying around so I didn't need either of those. He plays Crysis at mixed high and medium settings at 1280x800, not bad for less than 600 bucks. It's probably overkill for what you need, but here's the cart:
COOLER MASTER Centurion 534
Intel Pentium E2160
G.SKILL 2GB (2 x 1GB) 240-Pin DDR2 1066
Some may question my choice of CPU cooler, but I will say this. It's 100 times better than stock and with artic silver it idles at 37C and loads around 46C, that's all I needed it to do. If you want it cheaper drop the 9600GT for the 8600GT I recommended and drop the ram for the G.Skill DDR2 800 for $45. With the cheaper ram and video card it should come to $420.