What Should I buy a used Nintendo Wii or An Xbox 360 arcade.?

okay.... my brother has an Xbox 360 pro and hes taking it with to college in a COUPLE MONTHS. So i already bought games for it and my dad said that when he leaves that he will buy another xbox....i dont beleive him cuz hes just cheap like that.i dont wanna just give my brother those games i bought. I dont even have enough money for an used xbox 360 pro or not used. I want a Wii too but I KNOW FOR A FACT that my sisters will be all overit cuz thier friends have one. They even suggested that id buy a wii. So i know that theyll be all over it. just like they were all over my gamecube .