a 4850/70 off ebay if you have the psu for it, something new... perhaps a 6770, even a 6750 would be a good upgrade from that scrap
Thanks for all the feedback
A total budget of <$200 should buy a HD6850 and a competent PSU to run it. For $150-$160 you might find a HD6770 and a reasonable PSU. $90-$100 buys a HD5670 or HD6670 and assumes your current PSU is a reasonable 300W-350W model. $70-$80 should be enough for a HD4670 or HD5570 which ought to run on whatever you have now.
Don't discount used. I'm still trying to sell my old 4850 for $45. That leaves around $4oish which should be able to get you that Antec 380W green. Might not have DX11 or other goodies, but the 4850 will game a lot better then the 4670 or 5570.
^yeah thats what im saying... not a bad deal you might even be able to land a 4870 for 60 if you play your cards right
on low settings and low resolution it will work...i wont ask you that no buy this or that :-)
It will just work , but it will frustrate the hell out of you!