What Graphics card would be best for me?

I bought a cheap gaming PC recently from Amazon and it runs games ok but some will lag and these are games like Trials Evolution & Batman Gotham City Imposters. I would like one that would be able to play GTAV IV, Battlefield 3, Call of duty and other games like that on Good settings but at a £100-£200 price range.

The picture is the specs of the PC. If I need anything else that would make it run the games I noted better add that to your comment. Also, (If it helps) I'm Running on Windows 7 Ultimate 64bit.

Hmmm I'd look at a AMD 6870 or if the budget will stretch a 7870/7850.

They tend to have the best price to performance of the AMD cards. Nvidia wise, maybe a 650 or 660 (660Ti if the budget stretches) 

my reccomendation would be, a phenom2 x4 965 + 650 ti boost/7850/7790

maybe you're fine with that cpu, but... a dual core

That was also my concern that the CPU may not be burley enough.

Get gpu first try that out see if your happy with that it would be a big upgrade.

I would purchase a GTX 650 TI BOOST because of the performance it can offer if you want a medium graphical experience, by the way although it's in the 600 series it came out this year :)

Im thinking about getting this graphics card but will it work with my GPU???

http://gpuboss.com/gpus/Radeon-HD-7850-vs-GeForce-GTX-650-Ti-Boost

that one should be just fine It is a great performing card.

love the fact that you got a dual processor build from amazon. i would reccomend a 6870 or a 7870 if you could save for a bit longer. on the nvida side i would say nothing less than a 660 ti