Well since the gaming market (especially Xbox) has been flooded by 9 year old who will buy anything with a gun in it, i think both the halo sales and the cod sales will have grown, but i think because the amount of kids that only play cod (which is more then the kids who only play halo IMO) cod sales will edge out halo sales(on just Xbox).

Ok, that last comment is just insane...I would say that kids that play both games are the exact same.  As for the talent, I've played Halo a couple of times in my life, and while I sucked (this was before I started playing fps games), after playing and getting better at mw2, they both require a lot of skill to get good at.  Saying a noob can just camp and do good is completely false.  I absolutely sucked for a while at this game and it was getting very stressful.  Even now, after I've gotten like 3 days into the game online, I generally do really good, but I still get noob stomped sometimes.  It is completely different styles, so you really can't say one requires more skill than the other.  As for being killed very fast, I'd rather have my game be at least somewhat realistic (even though war is still nothing like this, I would say the bullets required to kill somebody are pretty close on here at least to some degree).