The Steelers have less chance of making the Super Bowl than the Rams, I'm afraid. The AFC is really a tossup (though I'm inclined to go with New England over any other team), but there's no one in the NFC that's going to beat the Rams with consistency in the American Dome.
Take this with a grain of salt, I'm a diehard Steeler fan, but St.Louis ain't all that impressive. Granted homefield is a good thing for them, but their turnover rate is terrible and has lead to their loses. If they played better teams, they would have lost some games. I think St.Louis is easiest to get upset out of the two. However, New England is the dark horse, I really don't want the Steelers to play them. They are a scary team. The Steelers need to close the door on teams or they will lose in the second round. All in all, I still say Steelers will be in since the NFC is a lot tougher division than people think.
Actually, USC (with *two* losses), wasn't even ranked third in the BCS. Georgia was ranked ahead of them, and I'd think we'd agree that the SEC is tougher than the Pac-10. Look, I'll admit the BCS is flawed.