11/05/2007 at 01:00 PM EST
At 40, Julia Roberts
is comfortable settled in L.A. with husband Danny Moder and their three children. And she's not planning on expanding the household – unless it's to provide safe haven for a certain press-hounded young pop star.
"You only have so much energy and you want to put so much energy into each child," Roberts tells Vanity Fair
in its December issue. "I wouldn't know how to have five kids. And they're a really good trio, these three."
Roberts and Moder, 38, are parents to twins Hazel and Phinnaeus, who will turn 3 on Nov. 28, as well as Henry, who was born in June
. Asked if she has any weaknesses as a mother, Roberts replies that she's working hard not to be too overprotective.
"I'm sure there are lots of things ... that I could get pretty scared about, but then, that's no fun," she says. "I'm always like, God, they're going to get hurt. But they will get hurt. That's the thing. And [Danny is] teaching me to show them that they can get up from that, or show them how to jump off of it."
The motherly instinct seems to apply to other vulnerable individuals, too. Asked how she feels about Britney Spears
's recent troubles, Roberts says, "I see and hear what's happening to Britney Spears and it's all I can do not to move her into my guesthouse and say, 'Okay, this is how it's going to be!' And just take care of her."
Roberts says she and Moder are currently building a house in Malibu – a big step, she says, for a small-town Georgia girl.
"It was one thing to be a New Yorker," she says. "I wear that really proudly. I moved there when I was 17, and it's a city that means something to me. But Los Angeles has always intimidated me. So I think that him building this house is as much a marriage as our relationship is of the things that I love and that he loves. It's a place where I think we'll be really content."
As for the future, Roberts says her dream "is to be a highly fulfilled and productive stay-at-home mom and wife." But there are a few career goals she'd still like to accomplish.
"I would like to work with Johnny Depp
," she says. "I've known him a long time. I think he's so interesting, and I think we look alike in a funny way. So Johnny Depp. Johnny Depp and I will play brother and sister in something."