What is better to have a i7 with 2.2GHz turno boost to 3.1GHz or i5 2.5GHzto 3.1GHz please help!?

To answer your video card memory question.the laptop only has a 1366x768 maximum resolution.graphics cards with only 512MB could easily handle that.2GB+ cards are intended for 2560x1600 resolutions,or 1920x1080 but with huge textures.Although even if the laptop could reach such a high resolution that the 2GB would be useful,say for example you connected it to a monitor to game or something,then the GT 630M would not be able to keep up with performance,because it is a low end gpu.In order to make use of large amounts of graphics memory you need two things:a good graphics card,7850M or higher from AMD,or GTX 660M from Nvidia,and you need a high resolution monitor,because if it's low resolution you won't need as much memory,and if the graphics card itself is bad it won't matter how much memory you have.

as for the i5 vs the i7.The i7 is this case is a better choice,mostly because the i5 2450M is only a dual core cpu,typical desktop i5's are quad cores,but laptop i5's are always dual core.whereas the i7 2670QM is a quad core,hence the QM,standing for Quad Mobile.

for gaming you need atleast 4 cores,and since the i5 2450M is a dual core,and the i7 2670QM is a quad core I'd say the i7 is best.

also about the ghz since the i5 has 2 cores and the i7 has 4 lets do the math.

i5 x 2 @ 2.5GHZ = 5 GHZ

i7 x 4 @ 2.2GHZ = 8.8 GHZ

although when your gaming the processor always does turbo boost so both would have equal frequencies @ 3.1GHZ

although the i7 version laptop has 6GB of ram,vs the i5's 8GB you won't need more thna 6GB for gaming,8GB is ideal so that you never reach the max ,but you could,if the graphics cards allowed,max out Crysis and Battlefield 3 simultaneously at 4GB of ram.8GB is simply chosen more often because RAM is cheap currently and the more you have the less chance you have of ever needing more.

http://www.youtube.com/watch?v=57HgWGqP6cQ

SO I'd say go with the i7 pc since it has a quad core processor with 8 threads,vs the i5 which has 2 cores and 4 threads,the mobile i5 is comparable to a desktop i3.so lets see that comparison .

(pay attention to where it says lower is better and where it says higher is better)

http://www.anandtech.com/bench/Product/289?vs=287

so the i7 clearly wins.