Okay.. so basically i built a computer couple of years ago its now becoming slightly out of date and id like to be playing shogun 2 in all its glory because atm im barely playing on medium/High.. not getting above 30fps

My System

Amd Athlon x3 435 @ 2.9Ghz
GTX 260
4Gb Ram
Reso - 1920 x 1080 (playing on my TV because my monitors ******.. pardon my french!)

the problem is im stuck on whether i should be upgrading my graphics card or upgrading my CPU, can only really afford to do one and with the cpu i can only go so far.. think the highest clocked one is at 3.00Ghz either phenom x4 945 OR athlon x4 640. my motherboards abit old and dont really want to have to upgrade that because it means faffing and reinstalling windows 7 :/ LOL graphics card is no limit really just not something over £200 dont mind second hand either.. just as good in my own experience

So yeaa and recomendations would be much aprriciated.. thankyou