Multiple online acounts for halo 3?

[Healthquestion]

Right now my brother has an xbox 360 acount and uses it to play halo 3. And what I want to do is get another online halo xbox360 acount so that I can do ranked games on the same xbox is this possible? Mainly I just want to have a seperate online 360 acount so that I can play ranked games and level up on one acount and he can play on his acount. So can we use the same xbox? and also can we play halo 3 ranked games together?

 

[Minus63f]

go to gamestop or whatevers around, get an xbox live gold card, set up a new account, and it will sync into your system, then you will have account a (your bros) account b(yours) and 4 guests possibly for each. it is all on the same xbox..you can join eachother in a party or meet in machmaking

 

[the_fig_newton_monster]

Buy a new XBL Subscription and your good to go! Just make sure you choose the right Gamer Tag on your xbox. Yes you can play ranked together.

 

[chubosaurusxedge]

you cant have multiple acounts
you need to buy another xbox live subscription