Here's a chart comparing Intel Atoms to other low power processors and also against a consumer Core2 Duo desktop:
The funny thing is that with all the talk and hype about the low power usage for Atoms, most of this is lost with inefficient power supplies and the old chipset they use. I was very surprised to read on Toms Hardware that the smarter thing to do would be to build a Core2 E7200 series (or similar) and one could achieve the same relative low idle power usage of around 40 watts but have a multiple of the performance. So much for 4-8W processors when the motherboard/power supply combos are driving the total Watts up to 40-65!
I thought these might work well in servers as a brilliant saver of power but for only like $50 more one could build a core2 system that uses essentially the same power with 2-6x the performance.
Geek on.
Brad