Eight Pac-10 teams have played nationally ranked non-conference opponnents. Oregon State also played Boise State before the Broncos were ranked.
Only Arkansas, Kentucky, Mississippi State, Tennessee and Vanderbilt can make such a claim. Ole Miss also played Wake Forest before the Deacs were ranked. South Carolina and Georgia also have Clemson and Georgia Tech, respectively, looming on the schedule who are borderline top 25 at the moment.
So, in the Pac-10 that accounts for 90% while it's not much over half in the SEC, and mostly the crappy teams anyways.
Non-conference schedules:
Southern Cal: Arkansas[w], Nebraska[w], Notre Dame
California: Tennessee[L], Minnesota[w], Portland State[w]
Oregon: Fresno St[w], Oklahoma[w], Portland State[w]
Oregon St: E.Washington[w], Boise St[L], Idaho[w]
Wash St: Auburn [L], Idaho [w], Baylor [w]
Arizona St: N.Arizona [w], Nevada [w], Colorado [w]
Arizona: BYU [w], LSU [L], Stephen F. Austin [w]
UCLA: Utah[w], Rice[w], Notre Dame [L]
Washington: Utah St [w], Oklahoma [L], Fresno St[w]
Stanford: San Jose St[L], Navy[L], Notre Dame[L]
Games versus BCS conf. (includes N.Dame):13 (6-6)
Games versus other IA: 13 (10-3)
Games versus non-IA: 4 (4-0)
1 game remaining versus BCS conf. school
Florida: S.Miss[w],UCF[w],W.Carolina, Fla. St
Kentucky: Louisville[L],Texas St[w], C.Michigan[w], UL-Monroe
Georgia: W.Kentucky[w],UAB[w], Colorado[w],GaTech
Tennessee: California[w], Air Force[w], Marshall[w], Memphis[w]
S.Carolina: Wofford[w],FlaAtl[w],MTSU,Clemson
Vanderbilt: Michigan[L],Tenn St[w], Temple[w],Duke[w]
Arkansas: USC[L],UtahSt[w],SE Miss St[w], UL-Monroe[w]
Auburn: Wash St[w], Buffalo[w], Tulane[w], Arkansas State [w]
LSU: UL-Lafayette[w], Arizona [W], Tulane[w], Fresno St[w]
Alabama: Hawaii[w], UL-Monroe[w], Duke[w], Fla Intl[w]
Mississippi: Memphis[w], Missouri[L], W.Forest[L], NW St[w]
Miss State: Tulane[L], UAB[w], W.Virginia[L], Jacsonville st[w]
Games versus BCS conf.:15 (6-6)
Games versus other IA: 25 (22-1)
Games versus non-IA: 7 (7-0)
3 games remaining versus BCS conf. schools
2 games remaining versus non-BCS conf. schools
1 game remaining versus non-IA school
All schools in the SEC scheduled at least 1 game with a team from a conference that gets an automatic spot in the BCS. 9 of the 10 schools in the PAC10 schedule a BCS conference school.
In head-to-head matchups this season, the SEC has won 3 games, while the Pac10 has won 1.