The i5 3570k has an unlocked multiplier and makes overclocking your CPU easy. It'll allow you to boost the performance of your PC significantly.
I'd recommend you read some of the overclocking stickies here on Tom's Hardware Forums. It's a great place to start. If it seems to be something you're interested in, I'd definitely look into getting the 3570k. You don't have to overclock right away. You can wait until you feel comfortable and gain a better understanding of the concept.