It would help if you posted you system specs. Even if you get a good card, if you CPU isn't up to spec, it won't help.
You could look at newegg.
here is the link
http://www.newegg.com/)
It really depends on how much you are willing to spend. It should even be a bit better then the recommended specs as most games are still a bit choppy with that. I have a GeForce Fx 5600 and I have some issues with the game getting choppy. It's not too bad though.