Simple question, how many controllers for online play?

Hey everyone. :D This is a simple question, but if I and a friend where wanting to both play online at the same time with two controllers, would this be possible? Does it depend on the game? (I'm mulling over if I should by an ethernet cable)

Thanks!

It depends on the game, most games with co-op allow 2 player split screen, some allow 4 player with two on each console and others only allow one person per console.

Only some games offer spilt screen LIVE I and only a few that allow a "guest" to enter without a live account It would be worth doing some researc into specific games.

Thanks guys. I really appreciate the help.