first you should convince people to start accepting bitcoins, then people will automagically spend them and drive economy. until then: hold them and dont sell.
people should stop looking at mtgox price. if someone sells they bitcoins because maybe they have to, then there is no reason for others to sell too. If you believe in bitcoin and want to support it, then buy as much as you can afford, and let the price go up. Even speculating is not really good because you would have maybe less bitcoins but they would be worth much much more.