Which is More Green: The Hand Dryer or a Paper Towel?

Ever walk into a bathroom where you're confronted with these two choices?

I reach for the automatic hand dryer, but then I wind up having second thoughts. Is it really more green than using (possibly recycled) paper towels? Which do you use?I instantly go for the hand dryer, (I've even gone so far as to mention, out loud, to perfect strangers that "I mine as well save a tree") but then I end up having second thoughts. Those hand dryers are uber powerful--a lot more than say, a typical hair dryer.

Which do you think is more green?