N66u is a solid choice.. but, it's VERY HOT.. I run mine active cooled with the front shell off and a stationary 120mm @ 250 rpm, in the Summer when I got it, it used to run up to 80 Celcius on load..
Now max load during winter is 30 C and 40 C in summer. pretty big difference..
The first version of the N66u sold was actively cooled, but they switched to a larger heatsink and went "passive".. TBH, i think it still needs active cooling even with the larger sink..
That said.. I wouldn't buy an n66u TODAY, because of AC.. you can get the night-hawk router for $150 on sale these days.. so... that makes way more sense, it's almost 5-6 times more powerful CPU wise, has a good support community with the custom roms, and it's also got the 3x3 AC stream for _The-FUTURE_