The weather outside is frightful, but Zooey Deschanel helps make the climate inside movie theaters delightful in Elf (opening today). But it wasn't all cheery holiday fun. The 23-year-old co-star of The Good Girl was required to lighten her brunette hair to play Will Ferrell's love interest, and she insists blondes don't have more fun.

"It is all a lie," Deschanel says emphatically. "I'm never going to be blonde again. I'd much rather be a brunette."

Even if she disliked her makeover, the starlet enjoyed heating up Elf with a toasty rendition of the classic tune, "Baby, It's Cold Outside." And hey, this girl can actually sing! "I started out doing a lot of musicals," she reminds us. "So it was cool that I got to sing in a movie."

In fact, Deschanel keeps her vocal cords up to snuff by performing in the Los Angeles area with her cabaret act, If All the Stars Were Pretty Babies. "We perform like twice a month when I am home," she enthuses. "It is really fun, and we do old standards and we dance and sing. I'll go back and forth — I'll focus on [the cabaret act], and then, I'm psyched when I go off to do a movie, because I've been working on this other thing."

Seems unlikely that Deschanel will have a chance to get bored any time soon, as she gets plenty of variety in her film offers. While receiving critical acclaim for her work in indie films like All the Real Girls and Manic, she's also happy to do a big-budget studio comedy like Elf. "I love Christmas movies," she says, probably thinking of the tidy deposit she just made to her Christmas Club account. "I love the idea of a movie that could come back year after year, and that people would watch again on Christmas. It might hopefully get them in the Christmas spirit."