I spoke to an exec at a competing studio today, and they suggested that High School Musical 3 is a little like Sex and the City, the estrogen-fueled May release from Warner Bros. Carrie Bradshaw and friends started their meteoric run with a $57 million three-day haul, but the gals generated 46 percent of that business on opening day. "HSM is very female and very front-loaded," is that insider's description, and that's hard to deny. A staggering percentage of the movie's opening weekend audience was girls under 18.

How many of those 'tween girls will return to see heartthrob Zac Efron again? And can Disney transform the picture from 'tween phenomenon to broad-based family film? Those remain open questions. Given that Disney's Hannah Montana/Miley Cyrus: Best of Both Worlds Concert Tour opened with $31.1 million in February, then dropped to a $10.29 million second weekend, it's fair to expect a big drop for HSM3 in the upcoming frame, although maybe not quite as steep. I am calling for a possible $17.65 million, which would represent a 58 percent dive (compared to 67 percent for Hannah Montana). As for a total domestic take for the first big screen installment of HSM, $110 million-$120 million now seems like the ceiling.

Weinstein's Zack and Miri Make a Porno, starring Seth Rogen and Elizabeth Banks, will probably finish No. 2 for the weekend, with something in the $11 million-$14 million range. This R-rated comedy, in the Judd Apatow mold, has a chance to be the all time biggest opening for director Kevin Smith, topping the $11 million start for Jay and Silent Bob Strikes Back. It will also, however, be the weakest opening in Rogen's young career, trailing blockbusters like Superbad ( $33 million opening, $121.4 million cume), Knocked Up ($30.7 million opening, $148.7 million cume), You, Me & Dupree ($21.5 million opening, $75.6 million cume), The 40-Year-Old Virgin ($21.4 million opening, $109.4 million cume) and August's Pineapple Express ($23.2 million opening, $87.3 million cume).

The first of two Clint Eastwood-directed Oscar caliber films, Changeling (Universal), will expand this Friday after a meteoric platform start. This past weekend, the Angelina Jolie period thriller grabbed $32,600 per screen at 15 locations, which is spectacular. It will roll out to 1,800 or so playdates this weekend, and its Per Theatre Average could approach $6,000. I am forecasting an estimated $10.6 million and a strong third-place finish for this picture, which will likely earn Angelina Jolie a Best Actress nod at both the Golden Globes and Oscars despite mediocre reviews (only 52 percent Fresh on Rotten Tomatoes).

Saw V (Lionsgate) will have a big Friday, thanks to Halloween, but a 65 percent drop is essentially inescapable for Jigsaw in his most recent go-round. The bloody sequel could post a $10.3 million three-day cash grab, for a new 10-day cume of just over $46 million. Beverly Hills Chihuaua (Disney) will likely round out the Top 5, adding another $4.5 million and pushing Chloe the chihuahua's Mexican adventure to more than $83 million by Monday morning.

The underwhelming platform start for RockNRolla (Warner Bros.) doesn't bode well for its weekend expanion to 800-plus locations. The Guy Ritchie-directed gangster comedy managed a $20,600 PTA on 7 screens for its Oct. 10-12 opening weekend, but its Per Theatre Average dipped to just $6,100 at 22 locations in its second frame (Oct. 17-19), and slid to just $5,400 on 19 screens last weekend. There doesn't appear to be much appetite for this one on a wider basis, and I am expecting no more than $4 million and a possible No. 7 finish.

The other wide release is The Haunting of Molly Hartley, being rolled out by Freestyle Releasing on approximately 2,250 screens. The big name in this one isn't Haley Bennett, who plays Molly Hartley. The draw is Chase Crawford, from TV's teen hit Gossip Girl ... but this is still a non-starter. My hunch is that Haunting will only scare up $3.8 million, despite opening on Halloween weekend.

FINAL PREDICTIONS FOR THE WEEKEND OF OCT. 31-NOV. 2
1. High School Musical 3: Senior Year (Disney) — $17.65 million
2. NEW Zack and Miri Make a Porno (Weinstein) — $13.25 million
3. Changeling (Universal) — $10.6 million
4. Saw V (Lionsgate) — $10.3 million
5. Beverly Hills Chihuahua (Disney) — $4.5 million
6. The Secret Life of Bees (Fox Searchlight) — $4.1 million
7. RockNRolla (Warner Bros.) — $4 million
8. NEW The Haunting of Molly Hartley (Freestyle) — $3.8 million
9. Eagle Eye (DreamWorks/Paramount) — $3.3 million
10. Pride and Glory (Warner Bros.) — $3 million
11. W. (Lionsgate) — $2.6 million
12. Body of Lies (Warner Bros.) — $2.2 million