Ive been building gaming rigs for 10years or so, heres my current pc spec:

i7 920 d0 cpu ( socket 1366 )
Gigabyte ga-x58-ud5 motherboard
6gb patriot viper tri channel ram
asus 4870x2 tri fan gpu
60 gb g.skill sniper ssd
1tb f1 hdd for internal storage and many external hdd's
cm storm sniper case
kingwin mach1 900w psu

I build this around 1.5 years ago now except for the ssd which is a recent addition ( 2 x wd 150gb velociraptors in the for sale section currently ) and i can still run every game ive played inc crysis 2 at full settings, only game id have trouble with would prob be metro 2033. My cpu is overclocked from 2.66ghz to 4ghz on standard voltage on an air cooler.

Unless you do video editing etc you really really dont need 12gb of ram, infact its been proven by people that know alot more than me inc people i know who do reviews and tests for websites that theres no real world gain in having more than 6gb currently and if you plan to overclock which i highly recommend then having 12gb or 24gb will more than likely stop you acheiving a decent overclock.

To be fair your current spec is fairly decent anyway, have you looked into overclocking your current cpu at all just to get the most from your current hardware to prolong its life before having to upgrade. All does depend on what resolution your monitor is set to when gaming as well mate as if you have a low res monitor youll be wasting your money upgrading to high due to the components ie gpu only coming into their own at higher resolutions with AA etc enabled for proper eye candy goodness.

Dave.