Interesting, let's see how accurate it is for me.. since I know how many watts my computer uses.
Hmm... this seems to be for selecting a power supply?... Your computer doesen't draw nearly that much from the wall.
I have a 420W PSU.. It says I need a 312W minimum PSU.. That's probably true.
But at the wall, my computer only draws ~180W while starting up, ~168W while 100% CPU and 132W while idle..
I'm running a Mobile Athlon XP/2600+(2.08ghz) at 2.4GHz @ 1.65v
1x 512mb PC2700
1x 128mb PC2700
ATI Radeon 7000 series
5x 7200rpm HDD
CDRW..