In normal operation my PC plus monitors uses between 180 and 320 watts. It’s much more variable than I expected. The monitors by themselves account for a fairly stable 70 watts (30 watts for the 18.1” Sony and 40 watts for the 20” Dell). When “off” the monitors use 0.5 watts (more or less, that’s near the resolution limit of my meter). The PC draws 4.1 watts when “off”.
This machine uses a lot more power than a new Athlon X2 or Core 2 Duo machine would. I should probably upgrade to a shiny new dual core machine — for the good of the environment. (Ignoring, for the moment, that the machine I have now would likely end up somewhere it got used after I gave it to CRC and thus would continue to draw power.)
The ”40 watt” bulb that now lights my office actually draws about 37 watts and throws out more light than the 150 watt bulb (153 watts) it replaced.
The losers of this test were my speakers — which draw 15 watts while on and 14.8 watts while “off”. I unplug them when I’m not using them now.