OP:
well with your lowly cpu even a 5670 is going to be bottle necked you will be able to run things on on low settings likely, and the best answer you selected is absolute crap, 8 gigs of ram is going to benefit bak0n 0% in gaming and an i3 2100 is worlds different then the processor you have, so dont listen to this poster, overall you gaming experience will be okay but I would recommend saving up for a new build and upgrading soon.
personally I run a backup, 720p rig with an AM3 mobo, athlon II 240 @ 3.5ghz, 4 gigs of DDR3 RAM, and a 5770, it is able to do what I want it to, but any less gpu power, even at 720p which is a bit less then what your res is, then I would not be happy with the performance so personally I would upgrade your rig and get a bit better of a gpu, I got my 5770 in an open box sale at frys electronics for $100 which was a great deal for a backup, 720p gaming rig , imo
these days you could get a decent am3 mobo for like 50-60 bucks and a P2 955 for 120 or a cheaper quad for like 90-100, really inexpensive just fyi