'Veronica Mars'' Charisma Carpenter

Charisma Carpenter – who played snobby cheerleader Cordelia Chase on Buffy the Vampire Slayer – is sparring with another blonde out to save the world on UPN’s Veronica Mars. Carpenter joined the teen-sleuth drama this season as Kendall Casablancas, a former Laker Girl turned adulterous trophy wife. “She has no shame,” says Carpenter, 35. Carpenter talked with PEOPLE about keeping in touch with the Buffy gang, filming racy scenes and making time for family.

What made you want to play Kendall Casablancas?
The name is really spectacular. My manager was like, “It’s the best name in prime time.” I just laughed at him.

She wears a lot of skimpy clothes. Did you have to step up your workouts?
There was a lot of extra work involved to get bikini-ready. I don’t want anything to wiggle. Most of the time I meet my trainer at the gym and we do a lot of everything: weights circuit with cardio, football drills, sprinting with weights on the treadmill.

Would you ever do another Playboy spread?
I don’t know. I did Playboy for a very specific reason. Not only was it a good financial move, but it was about the place I was at in my life. I had just had my son (Donovan, 2) and I’d gained 50 lbs. during pregnancy. I wanted to get back to my old self. I wanted to feel desirable and sexy. So I thought, “What if I went full throttle?”

How is it shooting Veronica Mars in your hometown, San Diego?
The beaches in La Jolla are the best, and fortunately my husband (psychology student Damien Hardy) surfs, so there’s not a lot of bribing going on there. Today my son and I went for a stroll and saw the sea lions and watched the sunset and played ball in the park with our dog. It was an awesome day.

A lot of Buffy alums have new shows this season: Alyson Hannigan on How I Met Your Mother, Nicholas Brendon on Kitchen Confidential …
It was a talented group and we have a built-in audience. I follow all of their careers and try to catch some of the shows, but we’re not all hanging out and having viewing parties. Many of us are married, three of us have kids, and everyone is busy shooting. But I text message Nicky all the time, and Alyson just invited us to a party.

You also recently completed a Lifetime TV movie.
It’s called Flirting with Danger, and I’m Danger. She’s a femme-fatale type. I had a lot of sex scenes. I was shaking like it was the first time. I really had to remember that it was not me.

What makes the sex scenes so difficult?
I’m shy, and I’m in love with my husband and sex is something I only do with him, yet I have to believably pretend that I’m in love with some actor. You want to look good, so there are some self-esteem things as well. I wasn’t comfortable, but I had agreed to do this and it was showtime, so you just do it. No pun intended.

How do you balance career and family?
Delicately, for sure. The distance is hard. This week I asked my husband if my son could stay with me longer (in San Diego), and now I’m on the road, headed back home (to L.A.) and doing an interview while my son watches a movie in the back seat. But this job provides in a way that other lines of work can’t. Let’s just talk about how expensive nursery school is. That bill was a rude awakening for me.