Windows MacBook Pro Late 2011 model

I have a late 2011 model MacBook Pro running windows 7 through Bootcamp and while its pretty good at running high res games, i do still have some trouble with certain games (i.e. GTA IV, L.A. Noire, MW3) Its mainly low fps so i have to drop graphics to maintain. My native res is 1440x900 but i usually have to drop them to 1280x720-800 to get a fairly smooth run. Ive been looking at graphics updates and i know i cant physically change out the one installed in this one so im just looking for an alternative. If there are any thoughts or ideas let me know, also let me know if anymore specs are need for an accurate answer.