I purchased and downloaded BFBC2 through Windows Live. When I go to play online/multiplayer, I have to register with EA... I enter my contact information and then it asks for my serial key, so I enter the only key I have, which is the Game Activation key... which gives me an error saying it is invalid. Talked to EA support and they say contact Microsoft. wtf - how do I play BFBC2 multiplayer?