IW.net and VAC are so good!!!11
Cheat / Hack Free Games: The biggest benefit of using IWnet by far is the fact that you don’t have to worry about joining a server full of aim-bots, wallhacks, or cheaters. Or relying on the server admin of the server to constantly be monitoring, banning, and policing it. Modern Warfare 2 on PC allows us to control the quality of the game much more than ever before as well as utilizing the VAC (Valve-Anti-Cheat) system to keep games clean of hackers and cheaters.
Quoted from: http://www.infinityward.com/