mw2 is pretty fun however everyone in that game is a try hard and they are very cheap. fable 2 is super fun, especially if you like medieval games. splinter cell conviction is another one of my favorite games too. it takes skill and stealth...pretty cool
id get modern warfare 2 and halo reach for the multiplayer modes, even tho the single player rocks on both to, and gears of war just as its plain awsome
I can suggest you a game called prototype is specially of action you can see for it in youtube its a very good game buddy but in the games you put on your list i suggest you should buy gears of war 2 i love that game, halo reach and dantes inferno, but if you wanna see more style buy ninja gaiden 2