just FYI, MW2 would probably be impossible to have as a PC tournament.
Here are some suggestions for PC games to consider in the future (which we have never hosted):
Battlefield 2
Call of Duty: World at War
Call of Duty 2
Battlefield 2142
Enemy Territory: Quake Wars
Unreal Tournament 3
Company of Heroes
Warhammer 40,000: Dawn of War II
World in Conflict
Command & Conquer: Red Alert 3
Command & Conquer 3: Tiberium Wars
Command & Conquer: Generals
Supreme Commander
Age of Empires III
Sins of a Solar Empire
Empire: Total War
Civilization IV
Rome: Total War
Battlefield 1942
Star Wars: Empire at War
Serious Sam II
Halo 2
Halo
Half-life 2: Deathmatch
And of course the old fallbacks:
Counter-Strike 1.6
Counter-Strike: Source
Day of Defeat
Day of Defeat: Source
Call of Duty 4
Unreal Tournament 2004
Left 4 Dead
Left 4 Dead 2
Quake 3 Arena
Warcraft 3
Starcraft
Team Fortress 2