ColdFusion718,
I am planning on getting Thunderbird or Palomino.
Why would I get a slower fan? I think you can get same cooling performance from very high quality heatsink and slower fan as with cheaperer heatsink and very fast fan. The difference is that in the first case, your computer is quiet, and in the other, it is very noisy.
Noise becoming more and more important to me, since my wife is constantly complaining about it, and several people that I was on the phone with asked about the noise in the background.
In case of that newest swiftech heatsink with 80 mm fan, you can get a lot of air flow even with quiet fans.