So I was thinking about chaging my gamertag name and was wondering if that would unban me from Halo 2 since I was banned for no reason. Is the ban only on the gamertag name or would the ban carry over if I changed my name. (If that made any sense please respond )

Need to register a new one.

yeah you cant change it once registered. call and cancel it (or just let it go if you dont get charged for it) and register a new one. you are going to need a new HDD and eeprom as well (or buy a new xbox)