The thing with Renée is...

Had things been slightly different, Ren?e Zellweger might have been writing this interview instead of me. If she'd stuck to her original career choice of journalism, that is. But after taking an obligatory acting class for her literature degree, hey presto! - suddenly acting became her new career choice.

Now she's acting's 'everything to everyone'. This week she's a psychotic nurse in the very dark comedy Nurse Betty, and in three weeks she's the girl on the run with Jim Carrey in another gross-out comedy from the Farrelly brothers (of Dumb And Dumber and There's Something About Mary fame) called Me, Myself & Irene. Then, due out next spring, she's the absolutely British Bridget Jones in that much-vaunted diary movie of Helen Fielding's bestseller, with Colin Firth and Hugh Grant as the gents who vie for her affections.

As Betty in Nurse Betty, directed by Neil LaBute, the man behind controversial comedies In The Company Of Men and Your Friends And Neighbors, she plays Betty Sizemore, a soap opera-addicted Kansas waitress. Traumatised by the murder of her heartless husband (Aaron Eckhart), she begins to believe she's a nurse and the ex-fiancee of a doctor (Greg Kinnear) in her favourite soap. LaBute, who saw her as the loyal secretary who thawed Tom Cruise's heart in Jerry Maguire, knew she had to be Betty. 'I told them I didn't know what she meant in box office terms, but I wanted her,' he says. 'There were no qualms about that for me. There was no reading. It was just, "Can we get her?"'

'Betty's not a role people would normally see me right for,' says Zellweger, in her Southern-fried Texan drawl. 'The film is about a woman accidentally living her dreams. She's delusional and from being a generous dreamer she falls into a state called "dissociative fugue", which is something that can happen to protect the conscious mind after experiencing an unmanageable emotional trauma. It allows the person to continue to function by taking on a new identity and also wipes out their recollection of their past.

'I'm not a soap fan like Betty. In fact I didn't watch television beyond the seventh grade. I didn't seek out soap fans for my research although I have to admit to watching Days Of Our Lives while shooting and loving it. Nurse Betty, however, is no soap opera. Nor is it a Doris Day-ish kind of comedy.'

And neither is her next film, Me, Myself & Irene with her off-screen love Carrey playing a schizophrenic Rhode Island cop who has to escort the felonious Irene Waters (Zellweger) across state lines to answer her warrant. (Apparently Carrey and Zellweger had met at a friend's dinner a couple of years ago and not clicked, but during the shooting of the film Carrey, according to Peter Farrelly, fell in love with her. However, Zellweger's trepidation against on-set relationships meant they had to wait till after they'd wrapped.)

'This is a very different comedy, the sort where you have to be honest with the character and the comedy takes care of itself,' explains Zellweger. 'And then, of course, there's good taste, there's bad taste and there's Farrelly taste. You can't imagine some of the stuff these guys came up with. I still can't believe it. My dad's not going to believe this. In fact my dad can't see this movie!'

Seeing her in Cannes earlier this year, if she hadn't been there in an official capacity to promote Nurse Betty, Zellweger could have been just another petite (she's 5ft 5in tall), sparky blonde with a ponytail who swigs her mineral water from the bottle and has a laugh that projects across the room. For a small, slim, innocent looking girl, Zellweger's got one helluva chuckle. But then she's earned it. She is, after all, only 31 and since her first film, The Texas Chainsaw Massacre: The Next Generation (made with another now A-list actor, Matthew McConaughey, when they were both at the University Of Texas), she has had plenty to laugh about. She says she still has the scars from the chainsaw, although nowadays her scars are more likely to be caused by Hollywood agents flinging scripts at her.

The Zellweger story starts some time before Jerry Maguire. 'I never took acting classes,' she says in her girly voice. 'I just went along to auditions until somebody said OK and eventually the walk-on roles became a few words. Then suddenly I was cast in Jerry Maguire. That came like a bolt from the blue. I mean, really, I'm a dork. The idea that a dork was in a Tom Cruise movie is hysterical!

'I got a call saying, "You should go and meet this guy Cameron Crowe [director of Jerry Maguire] who's directing a big movie." I went along, had a really good time with Cameron in Los Angeles, then headed straight home to Austin, Texas, thinking the role of Dorothy was a little outta my league... Then I got another call to go back to read with Tom. I had to keep my hysterics at bay. The day before I'd run out of money in the laundromat and had to dry my clothes by hanging them around my living room. And then here I was reading for a role with Tom Cruise.'