You can get some benchmark comparisons here: PassMark Software - CPU Benchmark Charts
The GT/sec is explained at the bottom of this chart: Intel® Core™ i7 Processor Product order codes
I'm not up on the latest and most demanding games, but my understanding of the subject is that given a choice between:
A) A good CPU + great Graphics card
B) A great CPU + good graphics card
you should go with "A", since the graphics card makes the more significant difference in gaming.
Of course, "great everything" is, uh, great!