I've added a "whole house" surge suppressor at my panel. I also my components (other than my amps) on a Monster power center. However, in heavy lightning, I'll still unplug stuff. As for whether just flipping the breaker is good enough, that's a pretty good question. I would think that a hit a ways from you, that causes a temporary fluctuation of voltage on your lines wouldn't get through an open breaker. However, all bets are off if there's a strike near you.