THe prescott I ordered is a 2.8ghz, OC'ed a bit to 3.2ghz.
The stock heatsink that came with it had a CoPper Core (Better Conductor for thermal energy then AL) so there is really no reason to get after market heatsink, although i would recommend investing in some better thermal compound then what intel puts in there (self assembly Box) which is a T-pad. Also if you go higher then 500Mgz increase when OC'ing, its up to you to buy a faster (RPM) heatsink fan.
Now about temps, yes its true what u heard that Prescott's produce more heat, but Prescot's have a higher thresshold for max temps they can reach too > around 70c-76c,
while northwood's maxes out around ten degress below what P's can withstand. so in reality prescotts are the better overclockers , and test have proven it.
My CpU idels at 45c and under load (fryCry) temps are at 50c with stock heatsink and fan, but with silicone based compound (most prefer silver which is better), but i'm cheap > $2.00 at radio shack.
We only buy hardware so we can run software on it.