What’s new in college football in 2005? Plenty, starting with nearly 20 percent of Division I-A head coaches.

Eight conferences will use instant replay for the first time, six leagues will welcome first-year members, and a new poll will help determine which teams play in the Bowl Championship Series.

Amid all that change, Southern California remains a constant – the Trojans still are the class of college football.

With back-to-back national titles, 22 straight victory and a 36-3 record during the last three seasons, USC already has established itself as college football’s first dynasty of the new millennium.

If Heisman Trophy winner Matt Leinart and the rest of coach Pete Carroll’s Trojans add an unprecedented third straight national title, a case can be made that theirs is the greatest run in the sport’s history.

“It would be a tremendous accomplishment just from the standpoint of parity in football now,” said Miami coach Larry Coker, who was part of a Hurricanes program that won 34 straight from 2000-2003, but only one championship. “Getting there is very, very difficult, but to win those games would be a tremendous accomplishment. It’s never been done. That says a lot right there.”

Southern California coach Pete Carroll, left, embraces quarterback Matt Leinart after their 55-19 victory over Oklahoma in the Orange Bowl on Jan. 4 in Miami. USC is again the favorite to win the national title in 2005.

Eleven teams have won at least 30 straight games, but only Miami’s streak came within the last three decades.

“Our focus isn’t about any kind of numbers you can put up, or any championships or any of that stuff,” Carroll said. “It’s about practicing really well and battling every day. We do that kind of stuff, and we’ll be a good football team, and we’ll see how far we can take it.”

Leinart, the big left-hander with SoCal roots, shocked many – and no doubt deflated quite a few competitors – when he decided to return for his senior season.

After tossing five touchdown passes in a 55-19 Orange Bowl rout of Oklahoma, it was assumed Leinart would take his cool demeanor and pinpoint accuracy to the NFL, where he almost was assured of being the No. 1 pick in the draft.

But who needs a job when you’re having this much fun? Now Leinart has a chance to join college football’s most exclusive club.

“There’s a lot of preseason hype about Archie Griffin being the only two-time winner of the Heisman, but everybody on our team knows that’s not what I’m about,” said Leinart, one of nine returning starters to USC’s offense and one of two Heisman Trophy finalists in the Trojans’ backfield. Do-it-all tailback Reggie Bush is the other.

The Rose Bowl will play host to the BCS national-title game this season, and the Trojans are overwhelming favorites to be playing Jan. 4 in Pasadena. But there are other teams with championship aspirations, and Leinart should have plenty of company in the Heisman race.

In the Big 12 Conference, Texas could have its best team in the Mack Brown era, led by elusive quarterback Vince Young, who began his Heisman campaign with an eye-popping performance in the Rose Bowl. Oklahoma has to replace 11 players drafted by the NFL, plus 2003 Heisman winner Jason White. Having tailback Adrian Peterson, the Heisman runner-up as a freshman in 2004, is a nice way to start.

Michigan and Ohio State, as usual, are expected to make a run at the national title out of the Big Ten, and Iowa, with three straight double-digit-victory seasons under Kirk Ferentz, has nudged into the league’s elite.

There’s a new Vick leading Virginia Tech, Mike’s little brother, Marcus, and – unlike last season – the Hokies won’t surprise anybody if they win another Atlantic Coast Conference crown.

In the Southeastern Conference, Tennessee and LSU are loaded for a run for the Rose Bowl, while Florida is one of those schools banking on a new coach to change its fortunes. Urban Meyer, with his record of quick turnarounds and explosive offenses, has the Gators believing a reprise of the not-so-distant glory days under Steve Spurrier is imminent.

Speaking of Spurrier, the Ol’ Ball Coach returns to college football and the SEC with South Carolina.

“It was a lot more fun hanging around the SEC than it was the other league I was in a couple of years,” Spurrier said of his two losing seasons as Washington Redskins coach.

The Gamecocks probably aren’t ready to contend, but Spurrier makes them interesting. Especially when the Gators come to town Nov. 12.

Notre Dame has been more interesting than good in recent years. Charlie Weis was hired to change that. The former New England Patriots offensive coordinator brings three Super Bowl rings but no head-coaching experience to Notre Dame, which hasn’t won a national title since 1988. The Fighting Irish haven’t even won a bowl game since 1994.

Patience has grown thin at Notre Dame, as Tyrone Willingham can attest. He was ousted by the Irish just three years into a five-year contract. Willingham quickly was scooped up by Washington, where he’s charged with rebuilding a program that once was the jewel of the Pac-10.

Among the other notable new coaches, Ron Zook, banished from Florida, takes over at Illinois. Les Miles walks into a virtual gold mine at LSU, replacing Nick Saban after he bolted to the Miami Dolphins. Former Dolphins coach Dave Wannstedt returns to his alma mater as Pittsburgh coach, a job vacated by Walt Harris, whose Northern California roots led him to Stanford.

Instant replay took root last season in the Big Ten, which became the first conference to use video to review officials’ calls.

This season, replay goes national with all but two conferences – the Sun Belt and the Western Athletic Conference – planning to use some type of review system.

The WAC and Sun Belt are among the conferences with revised rosters in 2005, as the shuffling that started with the ACC’s raid of the Big East finally comes to an end.

Boston College becomes the third Big East defector, along with Miami and Virginia Tech, to join the ACC, which has split into two six-team divisions and will play a championship game for the first time.

The Big East rebuilds with Cincinnati, South Florida and Louisville moving over from Conference USA. The Cardinals, coming off an 11-1 season, enter the league as prohibitive favorites to win the title and earn the conference’s BCS bid.

As for the BCS, it had to be tweaked again when the AP asked BCS officials after last season to stop using its media poll in their standings formula.

Looking for a replacement, the BCS hired a marketing firm to create a panel of former players, coaches and administrators, along with some media members, to vote for a new top 25.

The first Harris poll won’t be released until Sept. 25, four weeks into the regular season and three games into USC’s quest for a three-peat.

“I’m hoping,” Carroll said, “we feel comfortable with the spotlight.”