4 is probably doable, though the 860 does run hot. However, 4.5 is a bit high. Another cooler for really high OCes is the Prolima Megahalems. It is more expensive, but it does cool better than the 212+ (however most don't need that extra cooling, but your OC would).
You learn to read many posts, read many reviews and tests of the best heatsinks, you learn to apply thermal paste correctly, and what push pull fans mean etc etc etc etc.
I can tell your new to overclocking. You cannot guarentee you can get 4.0. You have to buy the best board and the top cooling, and good memory, and a top case to cool it all to even ensure you have the right stuff.
Then you have to know how to overclock. It's not a "Ronco set it and forget it" experiance.
You do your homework, you learn and hopefeully you can reach your goals.
A 860 can usually easily hit 4.0, but this isnt new folks that are doing this on these new chips.
You buy good stuff and learn to overclock, you can hit 4.1 probably on TOP air cooling.
You want 4.5 gaurenteed? Once you are capable of 4.1 easily, I'll set you up with a phase change builder who can make you a rig delivered worldwide for $1250. Ohh he lives in Finland BTW. No wareenty either. Guarenteed -100C temps at idle.