I am trying to build a computer for my brother. He has $400 bucks and I was searching on newegg.com. I know how to put stuff together, but I don't know how to buy ? He wants a fast computer for gaming mostly, do I want AMD or Intel ? and how do I know what motherboard to buy ? what case to fit the motherboard ? and what processor to fit the motherboard ? Can somebody list some good items to look for ???