a gulftown would only show its colours when your running apps like 3dsmax. the rest of the time 2 cores will sit idle and you wont see any real performance gains in games. 2 gfx cards on the other hand would show quite an improvement on higher requirement games... personally i would go for the 2 card setup as your cpu is pretty good and will do 3.6-4.2ghz with cooling. which should be enough to hand both them cards. and any game.
although the x6 i7 is a great chip its very over priced for the performance you get. you can almost match it with a 2500k-2600k for a quarter of the money and can beat it on some apps that use x4 cores or less.
so no m8 i wouldnt go spending all that cash on the cpu, for very little performance gain.