She's a pop singer, a pinup-worthy beauty and a paparazzi favorite, but Jessica Simpson insists she's just "a normal girl."

With her fifth album in stores, a new music video on the way and a movie opening Friday, normal might be a stretch.

At least in real life. On the big screen, she plays a very normal discount-store cashier in "Employee of the Month."

The role is an intentional departure from her sexy stint as Daisy Duke in last year's "Dukes of Hazzard." But, says the 26-year-old starlet, it also represents a new grown-up chapter in her life as she learns to take charge of her career, her future and herself.

"I'm kind of doing it by doses and, along the way, figuring myself out and learning to belong to myself, learning to be committed to myself," she says. "I see a lot of change in my life right now. I'm really grasping hold of what I want for the first time."

What she wants is to keep on being superstar famous while growing as a performer on stage and on screen. She knows that means living in a fishbowl: her every move scrutinized, her love interests transformed into tabloid fodder. It means being followed by photographers and trailed by microphones that could capture her latest language flub.

But she'll take all that.

"It's worth it," she says. "My career is more than what I hoped for."

The Texas-born blonde says that though she never expected to become a movie star, she's embracing the opportunity. Playing concerts around the globe and starring in the popular MTV reality show "Newlyweds: Nick and Jessica" prepared her for the challenges of acting, she says.

So far, she's stuck to eye-candy roles that call for short shorts and cleavage-baring blouses. But it's all on purpose and part of her plan, she says.

"I haven't wanted to take a lead role yet because I do want to learn," Simpson says, adding that she's happy to "take in that moment of just playing a straight-laced, normal, Midwestern all-American girl."

Greg Coolidge, director and co-writer of "Employee of the Month," says he had reservations when the studio suggested Simpson for the part. His concern: "Can she act?"

He was "expecting her to be bad" in "Dukes of Hazzard," he says. But when he saw her in a commercial for acne products, he was convinced she could handle the role.

"She was totally charming," he says.

The demands of the part were perfect for Simpson.

"Nothing against Jessica, but I had written that part just as sort of a device anyway," Coolidge says. "It's really not about her."

In the film, Simpson plays a pretty cashier who inspires a competition between two workers at Super Club, a Costco-type store. Both men (comedians Dane Cook and Dax Shepard) hope to win her love by earning the coveted title of Employee of the Month.

Cook says Simpson was well cast, serving as "the foundation" for the comedic jousting between the funnymen.

"I was really pleasantly surprised at how she came in and had plenty of ideas and held scenes together," he says. "She could hang in there."

To play the girl next door, Simpson says she had to "tone a lot down from Daisy Duke and from Jessica Simpson," referring to the sexy bombshell image she's cultivated since splitting from ex-husband Nick Lachey late last year.

"This (role) is not about my image," she says.