You need to list what else he wants to play...monitor included?
I mean comeon we can setup a single core amd and a 8 series card to max the game well enough...you don't need to spend 1000$ for COD4...if he wants to play the new COD when it comes out etc thats what matters....what power will he need for new games...because a singlecore ain't gonna kick it
I doubt he is building a pc just for one game...