Coming off their divisional road win over the Raiders, the Broncos went home for a Week 4 interconference duel with the Dallas Cowboys.  Denver would struggle out of the gates in the first quarter, as Cowboys kicker Nick Folk got a 49-yard field goal and running back Marion Barber would acquire a 1-yard touchdown run.  The Broncos would start to gain some momentum in the second quarter with quarterback Kyle Orton's 9-yard touchdown pass to rookie running back Knowshon Moreno.  After a scoreless third quarter, Denver would take command of the game in the fourth quarter.  The Broncos would get a 28-yard field goal from kicker Matt Prater, followed by Orton's 51-yard touchdown pass to wide receiver Brandon Marshall.  Afterwards, the defense would manage to hold off a late Dallas drive that actually made it to their 1-yard line. With the win, the Broncos would acquire their first 4-0 start since 2003.. How many yards was the longest touchdown play?