I have Carolina winning it 27-20.
Despite Denver's great defense, Cam Newton is a problem. Even if we go with a 4 man rush (which we used almost exclusively against New England), we are going to have a difficult time containing against his mobility. To compound problems for the defense, Carolina posted the second best rushing attack in the NFL this season. They can beat you multiple ways.
Denver's offense is the problem. While I agree that it is Manning's last hurrah, he is going up against the second best defense in the NFL, and he is doing so without much of a running game. That's a tough task for any quarterback.
I believe Denver will keep it close, due to the strength of the defense. But Carolina has the ability to create more opportunities for themselves, and they capitalize.