“High School Musical 3: Senior Year” and “Saw V” divided and conquered the movie biz over the weekend, opening with $42 million and $30.5 million, respectively.

Total B.O. rose about 30% from the year-ago frame, according to studio estimates, in large part because the G-rated and hard-R auds were almost totally distinct.

On the limited scene, Universal got spectacular results from 15 runs of “Changeling” in nine markets. The Clint Eastwood-helmed pic bowed with $502,000, or $33,441 per house. It breaks wide Friday in about 1,800 runs.

B.O. returns were not so rosy for sophomores “Max Payne” and “W.” “Payne” fell 57% to $7.6 million and “W.” dropped 49% to $5.3. Cume for the George Bush pic is $18.8 million, with a gross in the $25 million range likely after a post-Election Day exit.

The weekend’s top two films each entered record territory. Opening for Disney’s “HSM3” is by far the biggest ever for a musical, besting “Mamma Mia!”

Lionsgate’s “Saw” franchise is within $2 million of eclipsing “Friday the 13th” to become the top-grossing horror series ever.

“High School Musical 3” also raked in $40 million from 22 overseas markets. At $82 million, it was the first worldwide No. 1 opener since “The Dark Knight.” Disney said 35% of global territories are still to come.

“You’d never know we were supposed to be in a recession when you see two openings like this,” said Lionsgate distrib chief Steve Rothenberg. “When Hollywood offers up a choice, the audience can really expand.”

Warner Bros.’ “Pride and Glory,” a long-gestating New Line title, debuted at No. 5 with $6.3 million.

More than a few sighs of relief should be heard around Hollywood this morning given the big picture. Fall TV for the broadcast nets has been vexing, with continued audience erosion. The B.O. has been respectable but not exactly thrilling. And all sectors of the entertainment biz have been distracted by the unfolding economic chaos, which has yet to hit home in a drastic way but looms as a longer-term threat.

Meanwhile, Logo Features, the pic arm of Viacom’s gay cable channel, also got impressive results from “Noah’s Arc: Jumping the Broom,” which pulled in $161,302 from just five screens in an independent release.

Samuel Goldwyn’s “Fireproof” fell out of the top 10 in its fifth outing but dipped just 17% to collect $2.1 million, or $2,380 on each of its 898 screens. The cume for the Christian pic starring Kirk Cameron is now $23.6 million.

Sony Pictures Classics opened Charlie Kaufman’s star-studded puzzler “Synecdoche, New York” in nine runs, grossing $172,926 for an average of $19,214. SPC also ushered in “I’ve Loved You So Long,” which averaged $11,124 on six U.S. screens and $2,116 on four in Canada. The North American cume is $316,263.

Both “Saw V” and “High School Musical 3” were front-loaded. The horror pic did $14.2 million on Friday and $9.9 million on Saturday, while the tween tuner did $16.9 million Friday, fueled by boffo presales and a big sense of anticipation among teens, who tend to be Friday-centric. It dipped 10% on Saturday to about $15.3 million.

In the annals of modern media conglom synergy, the “High School Musical” franchise is among the most expertly executed and profitable examples. It is continually contributing revenue to the Mouse House — with minimal backend payout — across every tentacle of the empire. Incubated as a movie event for Disney Channel, the original has yielded spinoffs, soundtracks, live shows, merchandise and, of course, sequels.

Not long after “High School Musical 2” smashed records in August 2007 with a total audience of 17.2 million, an announcement came that the third installment would bow in theaters.

“Nobody knew exactly what to expect,” said Chris Leroy, Disney’s exec VP of domestic distribution. “This is new territory given that the first two were movies done for cable. We knew that we had a property with a very high awareness level. The other movie opening this weekend did what it does, and with the two of us, there was an opportunity to expand the overall audience. Audiences will come if you give them a reason to.”

Just as auspicious in terms of profits, Twisted Pictures’ “Saw” pics surpassed the “Halloween” series over the weekend. “Saw V” is the fourth straight pic in the franchise to open to at least $30 million.

“It’s really an achievement when you can get those kinds of numbers on sequels,” Rothenberg said. “There’s still a lot of juice left.”

Bow of The fifth “Saw” fell shy of the $31.7 million taken by “Saw IV” and the franchise-best $33.6 million from “Saw III.” Still, given that the five pics have come out in just four years’ time, the B.O. figures, not to mention the ancillary biz, are top-shelf.

Next weekend, which starts with the moviegoing-unfriendly Halloween holiday, will see the debuts of the Weinstein Co.’s “Zack and Miri Make a Porno” and Freestyle’s PG-13 chiller “The Haunting of Molly Hartley.” Warner Bros.’ “RocknRolla” and U’s “Changeling” also go wide.