Get the best cpu cooler that you can afford if you are overclocking. If you pay the extra bucks for the ability to overclock your processor, you may as well give yourself the tools to do it right.
Even if you don't want to push your chip to the limit, a better cooler with allow your operating temps to stay low which can only help your chip.
If you don't have the budget, there is nothing wrong with an air cooler. But, if you want the best cooling options, factory sealed water cooling units or custom water cooling loops is where you want to look.
I have an H100 Corsair and I have no problem at all recommending it or one of the other H series coolers to someone looking for the best cooling options.
Here are only a few of the benefits:
1) best cooling solution short of custom water cooling.
2) easy to install (pre applied paste is excellent)
3) smaller footprint which gives more room for air to circulate in the case
4) optimized fan speeds (I run mine on low: it is quiet and it keeps my 4.5 OC in the low 60s'C at 100% load)
5) much less stress on the mobo (some of the better air coolers are HUGE and HEAVY!)
Consider any of these depending on your case size:
http://www.newegg.com/Product/Product.aspx?Item=N82E16835181017&Tpk=h100
or
http://www.newegg.com/Product/Product.aspx?Item=N82E16835181015&Tpk=h60
Or even the Antec Kuhler:
http://www.newegg.com/Product/Product.aspx?Item=N82E16835209054
If they work even half as well as my unit does, you won't have any regrets spending the extra money on them!