amd phenom II x4 core vs i7 system ?

[TehDude]

Hi just wondering for what system is cheaper and better to go if the main purpose of the pc is gaming?.

 

[TehDude]

should the 4gb of rams do well on amd for games or i should go for 8gb instead?
and does the 8gb of ram would do a big difference for games or no at all?