Movies: Love--Actually!

Tricky business, playing the wife who is cheated on by a movie's hero. If you go too shrill and harpyish, you give the audience a chance to excuse him. If you play the victim, you give the audience a chance to hate him. Either way, it takes away from the tragedy.

Michelle Williams, 25, best known for TV's three-alarm teen weepie Dawson's Creek, gets it just right. When she sees her husband in a hungry kiss with another guy, she registers that horror-queasiness of having something she couldn't articulate become terribly clear. "Without her, this movie wouldn't work," says co-star Jake Gyllenhaal. "She adds a fourth degree. And I know I'm kissing her ass, but I don't care. She gives the best performance in the film."

Her onscreen husband and other co-star, Heath Ledger, struggles to think of anything to say about her. Perhaps that's because it's, you know, not very macho to talk up your fiancé and the mother of your child. "It was a big gift to have two people falling in love in our midst," says producer James Schamus of the duo's on-set romance."You forget how lovely that is."

It has to be noted that Ledger had developed a reputation for dating his co-stars. He had an on-off relationship with Naomi Watts, whom he met on Ned Kelly. But this one seems to be sticking, as evidenced by Matilda Rose, Williams and Ledger's 3-week-old daughter.

The two have quite similar backgrounds: both finished formal schooling early, left their family homes and started TV careers at 16. The parents of both separated. "Michelle's twice as uncomfortable in interviews as I am," says Ledger. He doesn't add, "And even better at acting." But we like to imagine he was thinking it.