I really have no idea who is gonna win this one. I think the Cardinals have a very good chance of pulling off an upset. I am not saying this because I hope they win, it is because of the reasons I am about to give.
While the Steelers defense is to be feared, they are physical and intimidating to say the least. The Cardinals defense has been playing very good in these playoffs and has seemed to come together and put out their best at the best possible times. The only problem for the Cardinals is they have not faced a QB as good as Ben Roethlisberger in the playoffs yet. Ben is a QB, but he can make a defense lose their confidence real fast. He is stronger than most linebackers and can break tackles that will drive a defense crazy. He also has a huge cannon arm that can force passes that none of the other QBs the Cardinals have played can get away with. In this match up, the Cards need to get inside Ben's head real early and mess with his confidence and timing. If Ben gets in rhythm, its all over.
The Steeler defense as fierce as it is, Kurt Warner is unlike any QB they have faced. He is fast at reading a defense, and the Eagles blitz about as good as anyone. Warner burned most of the Eagles blitzes. The problem with Warner is you can't read his eyes very good. He will look at one WR and throw the ball to a different one he is not locked in on. Warner is going to give the Steeler defense more fits and problems than any other QB they have faced. The only problem is, while the Eagles are good at blitzes, their blitzes are more simple and obvious than what the Steelers use. The Steeler blitzes and defense is more complicated and confusing.
While the odds should favor the Steelers, I still think the Cardinals can pull off maybe the biggest Super Bowl upset ever. Warner is very dangerous. While he lacks the rocket arm Big Ben has, Warner is faster at making reads and hitting the hot WR than Ben. With Warner vs Roethlisberger this will be a great example of smarts, coolness and wisdom(Warner), vs. raw power, brute force and size. Warner and Ben are as about as opposite of each other as can be. In this kind of game I would think it will favor Warner, but I will not underestimate Ben for a second, he is a great QB as well.