10% over thousands or millions of computers is a lot.
No it fucking isn't. This is the same bullshit bad math greenies are always spouting. "If everyone does a little, it adds up to a lot" Big savings require BIG changes on the part of each individual. If you save 4W displaying black screens on you LCD, even if you run it 24/7 for a year, you're only saving the equivalent of ONE FREAKING GALLON of gasoline.
Decaffeinated coffee? Just Say No.