USC will not go winless through the 9 game Pac-10 schedule. Nearly every other team in the Pac-10 is good, but none except USC are on that Michigan, Texas, LSU, Ohio State, Florida, etc. level. You string nine such games together, though, and USC will not make it unscathed through the conference. Possible for another split title with a Rose Bowl appearance.
That said, I obviously don't see USC as invincible as everyone else (don't forget road dates with Nebraska and Notre Dame) making the field wide-open this year. So wide open, in fact, I think we may see a suprise national title team. After Boise State's run last year, there is going to be a little more fluidity atop the polls this year, allowing that undefeated/one-loss team normally found outside of the national title equation, a shot.
My common sense pick to win the whole thing is West Virginia.