so i have about 100 hours in mw2 and i havent heard one person speak. i have mute all off and i use headphones normally high volume.... i dont have a mic my self tho but i doubt that has anything to do with it
Nobody cares to use headsets, and the people that do, either don't have anything to say, or are in a TS/VT server with the rest of their clan.
Why would people talk on PC? PC players can more often than not figure out that if the flag on C is flashing then it's probably being captured, we don't need to scream at eachother..
I play with my headset, and my mic connected but I'm usually in Teamspeak.
It's most likely just people are being anti-social in your game.
You can get into a match with your friend to test if there is a problem with your settings, but I'm guessing it's just the people you play with.