If all the top teams win out, I doubt these two would match up, only because of the selection order.
If the BCS standings stay the same, then USC would play Oklahoma in the Orange Bowl.
If the SEC champ doesn't finish in the top two, then they would go to the Suger Bowl. Auburn would get the shaft here, especially if they go undefeated.
Because the PAC-10 champ is currently ranked higher than the Big-12 champ in the BCS, then the Rose Bowl would make the next selection. More than likely they would use one of the at-large bids and choose California who would probably play Michigan as the Big-10 champ.
The Fiesta Bowl would get the next selection and have to choose between Utah as an automatic at-large team, Boston College as the Big East champ or the ACC champ. Virgina Tech is currently leading that conference, but they still have a game at Miami. If Miami wins the ACC, I think the Fiesta Bowl would choose them.
My BCS Bowl Projections (just for kicks):
Orange Bowl
Oklahoma vs. USC -2.0
Rose Bowl
Michigan vs. California -6.0
Suger Bowl
Boston College vs. Auburn -17.0
Fiesta Bowl
Utah vs. Miami -3.0
If one of the top three teams lose, then you can throw the above scenarios right out the window.
I'm hoping all the undefeated teams win out. This would lead to more pressure being put on the BCS to come up with some sort of playoff system. Personally, I'd like to see an eight-team playoff where the BCS bowl games would basically become quarterfinals. They should add three extra games to be played after the New Years Day games (two semifinals and the title game), and let the BCS Bowls rotate hosting the extra games.