I find it odd that the "65W" 4200+ I have at work runs frigid (barely spinning up the stock all-aluminium CPU fan a few times a day) but the "65W" E6750 at home never spins the fan down, even with a120mm fan on a big six-heatpipe cooler. I suspect Cool 'n Quiet >>>> EIST for power savings. Even the old S939 4600+, a 125w or so rated part, stays remarkably cool when it spends most of the day clocked down to 5x200.
another data point for you- I have an E6850 and with an all copper HSF from compusa, it never spins up its fan until I start playing video games. So the c2d is also pretty cool. I think E6850 is a 89W part isnt it?
before the e6850, I had a x2 4200+ that idled in the low 30s also. My wife has a pentium M 2.0 and at idle, it drops to 600MHz. I can see it in CPU-Z