That cpu is the best for gaming. Pair it with a ASUS Z77 V-Pro and you're laughing.
I agree with all of the above. But the best CPU won't make much difference if your graphic card isn't up to the task. What will you be using and at what resolution?
Well of course it would be, although you should focus on a better graphics card (assuming you don't have the "Best" Card In The World) for a better FPS. I think you would need a new one soon as you can. It really would be a great help but here is the thing you should get a better graphics card if yours is under the 6670's performance (that's pretty low) but if not have fun with the 2500k!
^ He has a 6870, so he won't have the best performance in the world, but it'll be better with the 2500K than it is with the Q6600, for sure.
If your 6870 is performing well enough for your liking then keep it. If not then have a look at the GTX 670 of the 7950. Both cards will be a noticeable upgrade on what you currently have.
^ Ohh I Missed That Part, A 2500k Would Be The Best Option!
If you can afford the CPU, board, RAM... go for a Sandy Bridge or Ivy Bridge upgrade. I didn't notice you said you had a HD 6870. That's an adequate gaming card up to 1080p resolution.