Always buy the best for your budget.
For gaming you will be best suited at an Intel i5 platform.
i7 is for number crunching really and the benefits are not seen when playing the majority of games out these days. I would concentrate on graphics card(s) with the money saved on i5 over i7.
Make sure you get a 64bit version of Win7.

Solid State Drives are beneficial if you can afford it. A smallish one for installing games onto is a wise idea.

Go onto overclockers forum and scout around and you can pick up on the latest, best value equipment pretty quickly.
Sites such as Toms Hardware are "usually" up to date and give a rough idea of where to start.