In general, AMD is usually king of cost:value for CPUs.
That being said, I believe the 2500k is currently the best gaming CPU.
is some ram for the 2500k)
I'd personally go with a GTX 560Ti, its about $100 less than the 570 and will do just fine with current games.
If you have the money, there is nothing wrong with getting a 570.
There are some things to keep in mind:
1) You might need to purchase a new copy of Windows if you had an OEM version on your last computer.
2) Your optical drives / hard drives may not plug in to the new motherboard. Open your case and see if any of the drives attach to the motherboard with a flat ribbon about 2-3" wide. If so you'll need to upgrade those components as well.
Please read through the thread thoroughly before responding.
Nobody wants to read a wall of text, formatting is your friend.
i5 3570k | 8GB G.Skill 1600MHz | R9 290 | SeaSonic 750X