If you want to overclock, which I presume you will be, then you'll want an aftermarket heatsink. The Hyper 212 Evo is a great cooler for the price and will most likely get at least 4 Ghz out of your 3570k. Don't forget you need a Z77 motherboard to overclock.
If you don't plan on overclocking, the stock cooler is ample.