If the engine fails in the hover (which is only about 4 -5ft), then you don't lower the collective and shove a load of boot in (which boot depends, as Whirly said, on which direction your rotors turn). Raising the collective helps to cushion the landing. Yes you have to be quick though! These failures are regularly practiced and aren't too hairy!
There is an envelope (affectionately known as "The Dead Man's Curve") of height/speed in which one doesn't fly as these are the points where the helicopter designer's think that survival is unlikely. You are taught not fly beneath this curve.
I'd still rather be in a helicopter than a Cessna if there's going to be an engine failure!
I hope that helps.