New i7 system

I'm new here, I hope you can help me

So my problem is this: I would like to buy a new PC, primarily to gamble. Initially wanted to make a Core i7 920 construction, but now I'm not so sure because I have heard the new processor only a minimal increase in power bring.

My system with i7 would then look like this:

CPU: Intel i7 920 ore
Motherboard: Asus P6T Deluxe V2
Graphics card: MSI n280GTX-T2D1G-OC
RAM: Corsair TR3X6G1333C9
PSU: Thermaltake Tough Power 750W Cable Management
Case: Cooler Master HAF932-KKN1
HDD: 1TB Samsung HD1030UJ
Drive: LG GH-22LS
CPU Cooler: Noctua NH-U12P SE1366


Without i7 processor it might look like:

CPU: Core 2 Quad Q6600 *
Motherboard: Abit IP 35 per
Graphics: Same as above, or a HD 4870 1GB, probably from Gainward
RAM: OCZ DIMM 4 GB DDR2-1066 Kit
HDD, PSU, chassis and drive: same as above
CPU Cooler: Noctua NH-U12P

* the Q6600, I would naturally orderliness over clock, I've heard that very well should be, can you confirm that?

Thus, there are the systems to be slightly and most importantly, how big is about the performance advantage (in%) of the upper to the lower system, which is already all around 254- 350 $ cheaper?

Thank you in advance for your hopefully many answers

the upper system is by far better
under the old system consists of hardware (motherboard and CPU), I will not say it is bad

I would say that you have to play without problems on the i7 renounce it, because you still will not so much, in my view is the i7 system if you only play the longer priced just not worth falling. and I also very often read / heard that the Q6600 is out of something, but I am just myself between dual and quad .

I am fully aware of what I wanted to know was whether even the upper system is worth. Of course you can also lower for a better ram and a better MB nehemn, but then one is priced quickly to the upper level of the system arrived.

Which components would you choose?
Can someone with a list of components that he considers good writing