I suck so bad at COD2! Not that I'm that much better at COD4, but I'm having much more fun with COD4 than I did COD2, thanks to the unlockable weapons and perks and challenges and all that crap. I doubt I'll ever go back to 2's multiplayer, since 4's is so good. (That's not to say that 2's is horrible or anything--it's great--but 4's multi is so much better, in my opinion.)
(Plus, I don't suck balls at 4 like I do 2.)
(Don't get me wrong, I still suck balls at 4, they're just not as big and sweaty as the ones I suck in 2.)