actually agree on the numbers (at least the numbers they mention). The dude claiming 750 MW-hours per year gets that number by assuming a 20% difference ((74W- 59W)/74W = 0.203 ) between white and black screens and only counts CRT monitors. He never claims that this savings is true for LCD. What he does do is assume that CRTs account for 25% of all monitors.

The WSJ blogger asked the Energy Star folks who asked the Cadmus Group to do a quick test. They found between 5% and 20% power difference between black and white on CRTs and no difference on LCDs. This doesn't really contradict the first article's numbers. He even confirms the 25% of monitors being CRT number, or rather, he states that 3/4 are LCD.

The real point here is that 750 MW-hours per year is (in more simple units) 8.6 x 10^4 Watts which is the equivalent of roughly 1500 60 Watt light bulbs. So Google switching to black background is the approximate equivalent of turning off 1500 light bulbs worldwide. That's a very, very, very small number compared to the total number of 60 Watt bulbs in use all over the world. Furthermore, nearly 100% of all monitors will eventually (probably very soon) be LCD, rendering those 1500 light bulbs moot. Oh well.

Ok. Time to get back to work.