So your baby bro is getting the mobo and the ATi.
What socket is the mobo, Socket 754 or 939? Cos if it is 939 give your bro the mobo, and buy yourselve a DFI Lanparty board that is PCI-e.
THis mobo will do you pretty well and if you decide to go SLIhttp://www.newegg.com/Product/Produc...82E16813136164
And then get yourself a 6800GS video card, really good for the valuehttp://www.newegg.com/Product/Produc...82E16814130258
And get another 512 mb ram, then you won't have to upgrade for ages, years.