We've been building various computers with different components and operating systems. After that we've been taking power measurements with a little device called a Kill-A-Watt, this basically gives you the wattage output of the machine you plug it into. It's interesting to see how the power usage levels vary from machine to machine. One PC used around 80 watts, while another was over 100. I'm not sure exactly what parts of a machine effect the overall power amount the most, or if the particular OS has anything to do with it. These are the computers we have logged thus far. We will be adding more as we build them.Computer 180GB SATA
Austin Power Supply
DR-B300ATX
AMD====> No CPU Frequency
K9VGM-V MS1 MS-7253-Ver 1.1
IDE CDROM
Nexenta 6Computer 2
Athlon 3400
M861G V16a
SATA 80GB
ATX 480W Generic PS82 WattsComputer 3
Allied Power Supply
Model AL - A250ATX
Max 250W
Debian OS100+ Watts