Don't get your hopes up on 5GHz. My 2600K can hit 5GHz but it just requires way too many extra volts to get it stable than I'm comfortable with for running 24/7 (have it at 4.8GHz for 24/7 use), the extra juice required for 5GHz is just not what I find to be worthwhile when considering the meager real world performance gains and the unnecessary extra power consumption and heat production.
of course there's always a chance you end up with a golden chip
For the best, look at the Noctua NH-D14. The 212 gives great value though just like many other coolers.
The NH-D14 is such a
huge cooler, and even the more modest tower coolers can be a pain in the ass to install, at least IMO. And for that price I'd rather go with an H60 or H70 (and some Gentle Typhoons in push/pull if maximum performance and noise are a concern) if only for ease of installation.
Its also much easier to cool a SandyB chip than a 45nm Nehalem