There's pretty good buzz coming out of last week's hush-hush staged reading of "Nine to Five," a musical based on the perennially popular 1980 movie about three secretaries who stick it to their boss.

Theater executives who attended the presentation were impressed with Dolly Parton's upbeat and witty score, which includes the famous title song.

The new numbers are "signature Dolly songs that also work as musical theater songs," one insider says, adding: "The show feels like a real Broadway musical, not one of those movies like 'The Wedding Singer' where you just shove the songs into the screenplay."

The book is by Parton's friend Patricia Resnick, who wrote the movie. Some people say her script isn't as strong as Parton's score, but you can bet director Joe Mantello ("Wicked") will crack the whip until she gets it right.

Insiders praise the three actresses who played the secretaries: "West Wing" alum Allison Janney, scoring big laughs in the Lily Tomlin role; Megan Hilty, doing a first-rate impersonation of Dolly (who's not in the show); and Stephanie J. Block, bouncing back spectacularly from the "Pirate Queen" debacle in the Jane Fonda part.

Marc Kudisch played the sleazy boss (Dabney Coleman in the movie) and hammed it up as only Kudisch can.

Parton was at the reading, standing at the back of the rehearsal hall, singing along with her songs and charming the pants off theater owners, who are eager to book a show that looks like a winner.

The first thing people notice about her is how tiny she is.

"She has this enormous head on this little body - well, little except in one area," says a source. "She looks like a Dolly Parton bobblehead."

This Dolly's no diva, by the way. Production sources say that when Mantello lets her know a number doesn't work, she tosses it out and goes right back to the keyboard.

Produced by Bob Greenblatt, who runs the Showtime network, "Nine to Five" is expected to open on Broadway in the 2008-2009 season.