They lost to Green Bay in the title game in 66 and 67, Cleveland in divisional playoffs in 68 and 69, lost to the Colts in 70, and won the Super Bowl in 71.
Of course, both Buffalo and Minnesota have lost four Super Bowls without winning one. Where the Eagles have been doesn't really matter. It's where they go from here. Of course, the Eagles are evil, so I'm hoping for a Patriots victory.
The Broncos were a team that couldn't win the big one until they knocked off the Packers in Super Bowl 32.