When Buffy met Scooby

Hollywood actresses are driven creatures. They just hide their will of steel behind bubblegum smiles and 'Gee, I don't know why it happened to me' psycho-banter.

That is, until you meet someone like Sarah Michelle Gellar. What Sarah Michelle Gellar wants, Sarah Michelle Gellar gets. Nothing unusual in that, it's just she's the first to admit it. Take Buffy, her most famous role, which brought her millions of fans and admirers (lad mags regularly vote her 'Sexiest Woman in the World').

The Buffy producers originally wanted to cast her as the lesser character of Cordelia. But Gellar was having none of that, and stubbornly kept auditioning until everyone agreed she was perfect for the vampire-slaying babe. Again, in her new film Scooby-Doo, Gellar had her say. She plays Daphne, a character you might remember from the cartoon as rather demure. Not any more.

'Daphne has been stereotyped because of her physicality. I told the director, "You have to keep Daphne real. It has to be about a girl finding her strength, finding her place,"' she says, jetting along at a speed even a tape recorder has trouble catching. 'I work on Buffy nine months a year, so if I'm going to use my three months off to do something else, it had better be damn interesting.'

We are sitting in Gellar's trailer at Warner Bros. She is tiny - 5ft 3in - and wispy enough to be blown away in a strong wind. But a brown belt in Tae Kwon Do makes her believeable at vanquishing vampires. Or Hollywood producers. 'Look,' she says, leaning forward, 'if you feel you can do something, you'd better say it - you can't wait for things to fall in your lap.'

So once Gellar convinced the producers that she was born to play a forceful Daphne, she eagerly commuted for two-week stretches between the Buffy set in LA, and Australia, where Scooby-Doo was shooting. Hard-working? Without a doubt - although she insists her personal life is just as important. She has yet to learn how to relax in an interview, however, and can leave the impression of being overly serious.

'I don't consider myself very serious, although I take my work seriously. I like to have fun! Who doesn't want to have fun? I have a life that makes me happy. I can lie on the beach all day and read a book and have no guilt whatsoever. But I can't live my whole life in the house. Internet shopping is great, but it's nice to try something on. I like Rodeo Drive as much as I like the mall.' Her look is Valley Girl vamp, a mix of chain store, designer and requisite Earl jeans. 'You see,' she says, 'I try to live as normally as possible.'

Key to her life beyond the film set is her poster-boy fianc?, Freddie Prinze Jr. The couple, who live together in West Los Angeles, met on the set of I Know What You Did Last Summer in 1997. They also act together in Scooby-Doo; he, rather aptly, plays Fred.

'Working with her was exactly what I expected,' he says. 'I know how much she shines. She truly loves to breathe life into a bunch of words on a page. I don't know anyone who has the passion for it she does. I see her read a script in bed at 2am and her eyes twinkle. I believe in her, and want her to be the biggest movie star in the world so I can retire.'

They seem well matched. Where she is all energy and enthusiasm, he is Zen calm. He seems to be the caretaker, looking after their dogs and cooking. They are rather like that other hot Hollywood couple, Reese Witherspoon and Ryan Phillippe (with whom Gellar starred in 1999's Cruel Intentions): two super-focused twenty-somethings who settled down much earlier than their partying peers. And, like them, it's the woman who wears the trousers. 'When I have kids, I'm not going to work,' Prinze says. 'If my girl wants to work, I'll hang with the kids and cook and clean.'