What games are you looking to play? You need more ram. At least boost your machine to 4 gigs. I was looking at these two cards yesterday which seemed pretty decent.
Asus HD 7770 2GB
http://www.memoryexpress.com/Products/MX39808
Asus HD 7850 2GB
http://www.memoryexpress.com/Products/MX39012
The 7850 has some pretty good reviews and isn't a ton of money. Keep in mind these cards are huge so you need the space to physically fit them in your case.