I think you mean 3570, not 3750.
No, overclocking is not required. But, for the $15 price premium, I would preserve the option and buy the "K" anyway.
A "K" will transform that 3.4 cpu into a 4.3 cpu with a simple and conservative raising of the multiplier from 34 to 43.
If you are near a microcenter, they will sell you a 3570K for $190, a good deal.