I'm not sure, but I was told for two people to use the same xbox that you had to each have an account through xbox live (which means you pay for two subscriptions), although I haven't tried myself. My friend and his girlfriend had to do that (from what he told me) to be able to play online together, but if anyone knows of another way, I would love to hear it. (what is this talk of a guest account?) I would love to get a few of my buddies together and play Rainbow six or GTA 4 online!!