Yes they won a super bowl in fact they won one 3 years ago and back in the day too but Peyton Manning was not the quarter back then
Through Super Bowl XLII, the Cowboys have not lost back to back Super Bowls. They lost Super Bowl V to the Baltimore Colts and Super Bowls X and XIII to the Pittsburgh Steelers.
Their last super bowl win was in 1995 with Steve Young as quarter back
Len Dawson, who was named Most Valuable Player of Super Bowl IV.