[1) Don't get a Prescott. They still run rediculously hot and require large ammounts of power, for little extra gain in performance. Get a dual core instead (and possibly switch to AMD).
The AMD's are a lot more optimized than the Intel ones, use less power, and also run cooler... Unfortunately the basic intel dual core offerings are quite a bit cheaper than the AMD ones at the moment. Tough choice. :-?
3) As for cooling, don't use Intels stock fan - it's useless. Get the in-a-box version for the extra warranty (if you want it), and then slap a high-end Zalman heatsink on it. In my own case this almost eliminated fan noise, and the CPU temp dropped from 60 to 37 degrees C.
That's the way to go, especially if you get a dual core chip, there's more going on, = more heat = more noise.