XBOX
Hit the xbox button on the controller and create an account for xbox live. Sign out first.
PS3
Log off of your current PSN and go to the icon for playstation network and there will be an option to make a new accoun tif you scroll up.
Computer
If you have xbox then you need an xbox live account or if you have PS3 you need a PSN account. Then go on multiplayer and select play online.
You get a friend that bought them and then you get there online account info and then you just download it on to your system
No
Yes you can play only CERTAIN games with a sliver account such as cod modern warfare and co modern warfare 2....those are the only 2 i know of that allows it
Yes
No
Yes, there is online multiplayer on Call of Duty 4: Modern Warfare.
It depends... If you want to play online for free... Ps3. but if you already have an xbox live account i would recommend it for the 360. Gl on Cod: Modern Warfare 2.
If for Xbox 360 you need an Xbox Live account, for PS3 you need a PSN account, and for both you need the internet connected to the console.
no only if you log into your account but player number 2 whont get those guns that you have on your account
its probably because you put your self as an under 18 year old on the settings when you first made an on line account you cant change unless you make another account.
there is none