Athlon vs. Intel Power Consumption
Athlon 64 for Quiet Power :: SilentPCReview.com. A good review of the power consumption differences. Has a great slide on actual power consumption of CPUs:
Basically shows that the new Intel Prescotts and Northwoods really burn up lots of power. Quite a reverse from the Athlon XP which was way hot and the original Pentium 4s.