Why Howling Mine and Ensnaring Bridge in the same deck, you ask? Simple. Most spells in this deck cost 1 or 2 to cast, meaning you can be almost certain of emptying your hand each turn by the time you have a Mine in play.
Also, here's a possible game for this deck.
Turn 1: Draw 7, Mountain, Bolt, go. 5 in hand. Opponent at 17 life.
Turn 2: Draw. Mountain, Bolt, Chain, go. 3 in hand. Opponent at 11 life.
Turn 3: Draw. Mountain, Chain, Tap remaining lands for RR, Fireblast, Fork. Opponent at 0 life.
Granted, that's ideal, but situations close to it aren't hard to come by. Fireblast/Fork DOES work, BTW, as you don't have to sacrifice another 2 mountains.