From the conclusion to the SPCR review of the Earthwatts:
Still, we're not really sold on the "Green" aspects of the Earth Watts. High efficiency, active PFC, and the required RoHS compliance all make good selling points for the Green conscious, but these features are not unique to the Earth Watts â€” all of these are hallmarks of good quality power supplies, "Green" or not. And how much impact does the extra efficiency have, anyway? We're all for efficiency and being environmental friendliness, but we find it hard to believe that the energy saved by the extra efficiency is all that great, especially at the 40~60W level that a well-designed system should idle at. The 6~8W difference between 60% and 70% efficiency at this level just doesn't seem like much. It's certainly not enough to justify buying a replacement power supply if the environment has to bear the cost of putting the old power supply in a landfill.