In David Mamet's magnificent new comedy State And Main, Sarah Jessica Parker - possibly best-known for lending her services to the unutterably vile TV series Sex And The City - gets to keep terrifically good company, with the likes of Philip Seymour-Hoffman, William H. Macy, Alec Baldwin and Rebecca Pidgeon also on board.

It's a surprisingly gentle satire about a film crew descending upon a small New England town, with Parker in top form as difficult-but-daft diva Claire Wellesley, who decides at some point in the shoot that she will no longer get her 'puppies' out for the lads, in spite of the director(Macy)'s observation that America "can draw her tits from memory". (Parker, it must be pointed out, has always refused to do nudity on screen, and unlike most of her peers, this includes those instances 'when the plot demands it'.)

What's surprising is that such an accomplished veteran of the stage, film and TV circuits found her role in State And Main challenging and often downright terrifying.

"After a few days' rehearsal, I returned home to New York convinced I'd be fired from the movie, and I jumped every time the phone rang. And it's not like I'm insecure about my abilities. It's just that I'd never encountered a director who was such a challenge."

True, Parker would not be the first to find the notoriously intense Mr Mamet more than a little intimidating - but even allowing for the fact that "he was always reshaping dialogue", and Sarah's subsequent fears that she would fuck up Mamet's "beautifully constructed language", it is difficult to picture Parker being nervous of anything. Having made her network-TV debut at the tender age of eight in an NBC production of The Little Match Girl, she swiftly graduated to become Broadway's third 'Annie', despite having had no formal training at the time: "I remember getting up on stage for Annie every night, singing with a full orchestra, and I was just so fearless. And being fearless is what it's all about."

After this early Broadway debut, Sarah went on to dance with the National American Ballet Theatre and sing with the New York Metropolitan Opera. However, it wasn't until a short-lived sitcom in her late teens (Square Pegs) that she achieved national recognition, cemented by playing opposite Chris Penn in 1984's Footloose as a gawky dance-loving adolescent, in a role which won her the Young Artist Award for Best Young Actress.

In the 1990s, she won acclaim for her work as a gum-popping Valley Girl in LA Story (1991) and an anxious bride-to-be in the screwball comedy Honeymoon In Vegas (1992). Most memorably, she was the failed director's shrew-like girlfriend in Tim Burton's unheralded masterpiece Ed Wood (1994).

All the same, none of these roles led to a place among Hollywood's A-list of leading ladies. This isn't all that much of a surprise when one considers Parker's attitude to movies: she has always remained New York-based, and has regarded screen roles predominantly as paycheques to finance working in theatre.

"In theatre, there's a work ethic," she observes. "No-one gets you tea, or drinks, or a chair. It prevents me from turning into a pampered star! I actually like to live that way - just doing great plays in New York."

Theatre may be her primary vocation, but it's her work in television which has catapulted her into superstardom: specifically, her role as Carrie Bradshaw, chronicler-in-chief of the sexual misadventures of her merry band of neurotic, predatorial, man-or-beast-hungry mates. While some of SJP's past high-profile romances - notably with Nicolas Cage, John F. Kennedy Jr., and Robert Downey Jr. - might suggest a romantically misspent youth, she insists that her own experiences "were not at all colourful. But that's why Carrie is so much fun to play. Because I'm not at all like her. Her life is totally different to mine and I don't relate to it at all."

Indeed, Sarah's existence really does seem considerably more mundane than anything portrayed in Sex And The City. She's a devoted member of a book club, she insists on doing "ordinary things like riding the subway", she prefers staying in with her border collie Sally to clubbing, and she's been with long-term partner Matthew Broderick since 1991. After she publicly announced her intention to marry him - live on the David Letterman Show, back in 1997 - he duly proposed backstage, and the pair were married three months late in a small synagogue on New York's Lower East Side.

If her life seems unpretentious and a mile removed from the Manolo Blahnik-heeled world of her televisual alter-ego, this can undoubtedly be attributed in part to her utterly humble beginnings in Cincinnati with three siblings and four step-siblings all dependent upon her stepfather's income as a truck driver.

"We didn't have any electricity sometimes," she recalls, "we didn't even have Christmas sometimes." Nonetheless, her obviously strong-willed mother made sure to immerse her children in the arts - saving up to take them to symphonies and ballets, while vehemently discouraging them from lowbrow pursuits such as watching movies on the family TV, which was reserved STRICTLY for news broadcasts. "When Mom came home from work, she'd put her hand to the set, and if it was still warm, her hand went directly from the TV to your face."

Following State And Main, Sarah can next be seen in a dark romantic comedy about a woman who falls in love with the hitman hired by her significant other to kill her. The film boasts the magnificent title Life Without Dick - literal proof, if any were needed, that Sarah Jessica Parker genuinely does have nothing in common with Carrie Bradshaw and co.

State And Main opens nationwide on March 30th.