So the only reason PC users are upset is because they have to pay the same price as everyone else for the same game?
That should really be for a different thread (like the Modern Warfare 2 thread) as I think people want this one to concentrate on multiplayer strategies, but since it is related to multiplayer, I'll quicky explain.
PC Games have had certain standards since over a decade ago. Dedicated servers were one of them. This is a server that's always running, often paid for and run by the community. You can usually find a good server and always go back if you like the community. Good servers kick hackers and douchebags keeping the play environment clean and fun. Some run mods that customize the game in a way that the community finds fun.
Another thing is that dedicated servers allow clans to practice consistently on a server which they can invite others to with a simple IP address (like a URL). Dedicated servers also ensure fair play as the host of the game does not gain an advantage and there's no issues if the host drops from the game.
For Modern Warfare 2, Infinity Ward decided not to do that and port the console version's system (random matchmaking) instead. People were not happy with this. IW keeps saying it's because their system is better, but the real reason is control. With this system, user mods are not possible as you have to be using the same standard that they dictate. You must have their DLC to play on specific playlists (think Halo). You must pay them to keep up. Kind of a shitty move on an open platform.
It's also obvious no work was done on the port when the error message on PC specifically says your version of "Xbox Live" is not up to date.
This is all on top of the $10 extra they're charging even though the PC has no licensing fees like the consoles do.
Like mentioned, there are plenty of better games out there for people to play instead and I'm sure people will opt to take that route. Left 4 Dead 2 in 7 hours should keep people busy!
But again, let's not shit up this thread for people enjoying the game by getting carried away with this discussion. If anyone would like to talk about it more, please do so in this thread:
http://www.smogon.com/forums/showthread.php?t=56855