The Vikings defense is only so deep, and they are not the Monsters of the Midway style defense. The meat of the team is in the trenches. Outside of the linemen, there are a few good players, but no Mike Singletary or Dan Duerson on this team, although you can argue Jared Allen is as close to any defensive player from the Bears Super Bowl team.
The Colts, not a defensive powerhouse, but did very well in stalling a vastly improved Baltimore offense this season, and forced Flacco to throw more than Cam Cameron hoped for. The lack of a disciplined defense killed the Ravens chances, and the offense was forced into 4 turnovers. The Colts do not have the defense to carry them if the offense is stymied by the Gang Green in the AFC Championship Game. Peyton Manning has to make plays on behalf of the defense, who could get ripped up by the Jets ground game.
As for the Saints, don't expect what was seen against Arizona. This will be a game very similar to that of the Saints game against the Jets early in the season. Well, maybe a few more touchdowns between the two teams, especially since its Brett Favre and not Sanchez, but this will not be shoot-out by any means. I don't know how well the Saints defense can hold up against a very talented group of skill players in Peterson, Rice, and Harvin. Brett Favre has been here plenty of times, and this New Orleans team ... not so much.
NY Jets (+7.5) @ Colts, and I'll take the over at 40
Vikings (+4) @ Saints, and I'll take the under at 52.5