The i7 is better if you do stuff other that gaming because it supports hyper threading. Generally stuff that uses a lot of threads like rendering 3d models and such.
But for gaming use the 100€ or $100 price difference is usually too big to justify the tiny improvement ( if any ) in performance.
So I would say that if you want to get the i7 instead of the i5 , you can. But your experience in gaming won't really change.