Also, in X-Wing "Isards Revenge" a squadron of X-Wings destroyed 4 AT-ATs with only their laser cannons and implied that a single Proton Torpedo could have finished each. You have to remember that at Hoth the rebels only had very outdated weapons for their Snowspeeders and defenses, the only notable defence they had was the Ion Cannon.
"It may be that the old astrologers had the truth exactly reversed, when they believed that the stars controlled the destinies of men. The time may come when men control the destinies of stars." -Arthur C. Clarke
"Ideals are like stars: you will not succeed in touching them with your hands, but like the seafaring man on the ocean desert of waters, you choose them as your guides, and following them, you reach your destiny." -Carl Schurz