Your ideal gaming MHZ is between 4.2ghz and 4.8, depending on how lucky you are.
I feel that 3.7ghz max turbo is a little on the low side and you may see your GPU being held back a little. It all depends on the game and how it's coded really.
Personally I would not buy a I5 any way. You can always get the equivalent Xeon for less money. There's one set up like the I7 for just a little more, I would go with that.