How should I build my computer?

I want to build my own computer using NCIX.com and I'm from Canada. I'm looking to play games like WoW, Diablo 3, Minecraft, CS, Rift, Hon and maybe a couple other games, but I'm not really a computer know it all so I need some help and I can only go as high as $1400-$1500 so if someone could give me some pointers and suggestions that would be awesome.