Which is better for gamming?

Intel core i5 processor with turbo boost
Intel pentium g645
2nd generation intel core i5-2320

Answer fast please. Important

Kinda Vague question if you will use a cheesy board or onboard video chip instead of stand along card.

A friend has a i5 2500 and loves it

Core i5 processors are good for gaming.
An Intel Core i5 2320 is a product of the 2nd generation core i5 processors (named "Sandy Bridge"), and it has turbo boost.

Any of the Intel Pentium G-series processor are not recommended for gaming... They are slow processors.

If you are going tu purchase a new Intel Core i5 processor, I suggest you to get a 3rd generation one (named "Ivy Bridge"). It has a better integrated GPU, better clock speeds and new awesome features.

The i5

But as mentioned, youll want a decent motherboard and dedicated graphics card for the best gaming results. This would be the recommended solution for gaming.

If you plan on using onboard or integrated graphics, gaming performance will not be that great as its meant mostly for multimedia purposes.
However, if you still go this route the i5 2500 would likely be the best option.