i3 is cool, but an i5 is fit for any gaming needs.
And lets not forget about the videobord. Dont get excite when you see 2 gb or shit like that, what i recommend is any nvidia GeForce from 460 till 670 but it always must be a GTX and a TI is a +
Intel, and screw everything that says ATI / AMD. Its no decision to take here, no brainier really. If you get an AMD cus a friend has one or endorses it, its just cause they literary lie to themselves.
Get an ati now, lose driver support in 2 Years +-, and lets not talk bout AMD'S.