So recently I bought Battlefield: Bad Company 2 off of Steam, and needless to say (after a bit of tweaking because my computer kind of sucks) it is a lot more fun than Call of Duty MW2. The multiplayer is extremely fast-paced, and a lot more challenging than MW2. I would definitely recommend it.
On another note, it turns out that my dad is friends with the executive producer of Treyarch, and we are getting in on the Call of Duty Black Ops beta. Hell yeah, should be nice.