By IAN SPELLING

"When we started Charmed, we had no expectations," Holly Marie Combs says. "We knew that we were having a good time.

"We didn't receive a lot of publicity," she recalls. "I think that Felicity was the big show that year, and Charmed was kind of in the background. So we were really surprised to last so long, and we're all still surprised."

The year was 1998, and the WB quietly cast its Charmed spell, introducing Combs, Shannen Doherty and Alyssa Milano as the sisters Halliwell -- Piper, Prue and Phoebe -- good witches who use their powers to save the world from evil. While other shows burst on the scene and then imploded, Felicity among them, Charmed steadily grew in popularity.

Now in its seventh season, the series continues to thrive. Fans quickly embraced Rose McGowan, who signed on to play half-sister Paige after Doherty exited following Season 3. And Piper -- thanks in part to her relationship with Leo (Brian Krause), which resulted in the birth of a child, Wyatt -- emerged as the show's heart and soul.

"My character has gone through so many changes, really," Combs says. "Piper started out as a very insecure, modern woman trying to control everything. She was kind of neurotic. She's evolved into a mother and wife and the head of the family. She's matured greatly.

"That was very important to me -- that, in the midst of all this supernatural stuff that we do, we also portray real women with real problems, and we show the evolution we all go through in life," the actress says. "It's hard for people to relate to being a witch, but it's much easier to relate to a woman who's got sisters, a husband and children."

Combs makes a point of expressing her delight at this season's array of guest stars: Nick Lachey is on board as Phoebe's love interest. Charisma Carpenter recently turned up as a demonic seer and will be back for more. Kerr Smith of Dawson's Creek recently kicked off a long stint as Agent Brody, who discovers the girls' secret and romances Paige.

"It's nice to know that people still want to come in and work with us," Combs says. "You never know, because after seven years people in the industry can be saying, `Oh, God, is that show still on?' So we're lucky. We're still on, we're still doing well, and people like Nick and Charisma and Kerr want to be with us on Charmed."

And how about Combs? How hard is it for her to stay interested?

"You know what? It's not," the actress says. "We have such a cushy job. We're so spoiled; they treat us so well. Charmed really lightens up people's week, and it does a great service. We're just here to entertain -- we're not brain surgery.

"As long as there's still an interest and as long as people are still coming up to me and saying, `I love your show,' it's easy to stay interested," Combs says. "In my personal life my priorities have shifted -- I have a son. But as long as I can make time for him, I'm OK."

Right now Charmed, which airs Sundays on the WB, is as strong in the ratings as ever. Combs, McGowan and Milano are under contract for one more season, which means that Combs most likely will be back in her director's chair at this time next year.

"I think there's a bad karma attached to an actor wanting to get out of a successful show," Combs says. "It's like looking a gift horse in the mouth, and I just can't condone it in any way."