OK, so I just signed up for this deal -- and it's nice to be able to try it out.. but I also have another valid ID with another game I bought... etc.. how long can you keep switching between these and get another 2 months free if at all???

Do they track your name, address or credit card???
do you have to switch your callsign online or what?

Thanks for the help

I'd look at the terms/conditions of the key. I was wondering the same thing though, but I don't even have my xbox yet. Anyone?

My guess is that you can't stack them as people give them away pretty freely on here and other boards.