@ _Yank: I would advise you to use a quad core cpu for games. It´s better to use a quad core cpu with less power as for example a dual core with much power
8gb is a waste of money, with tha money you can upgrade other components, with 3 - 4 gb is enough.
8gb = 40-50 euros, you can get a bit better videocard, like instead of a 6950-6970 (for example) or instead of a 550ti to a 560. 3gb = 20 euros 4gb = 25, if you get a pack of 2x 4 gb you get a discount, so it's worth it.