After filming the just-released Vanity Fair, the golden-tressed star of MGM's Legally Blonde movies went brunet. Reese Witherspoon didn't change her signature look for purely cosmetic reasons, though. Going darker was a must for her next role as the late country songbird June Carter Cash in the upcoming Johnny Cash biopic, Walk the Line.

"I was desperate to play June," the 28-year-old actress says. "I would have walked on my hands and knees to Memphis to play the role. I grew up in Nashville, so country music is part of my heritage. There's something amazing about the love story between her and Johnny Cash [who's played by Joaquin Phoenix in the film].

"These were two people who were meant to be together and had to work side by side for years before they were ever able to express their love," she continues. "It was tumultuous and hard, but that's what relationships are. It's been one of the hardest movies I've had to make, but it's been very educational and enriching."

Witherspoon's taking a break from shooting Walk the Line to promote Vanity Fair, the umpteenth screen adaptation of the seminal British novel by William Makepeace Thackeray. According to the actress, what makes this version special is director Mira Nair, the Indian filmmaker behind such critically acclaimed movies as Monsoon Wedding and Mississippi Masala.

"Mira and I collaborated very closely on this film," she explains. "It was nice being able to come at the book with a fresh perspective with someone like Mira, who is also an outsider to British culture."

A potential problem arose when Mrs. Ryan Phillippe discovered she was pregnant a few weeks before shooting was to begin. "I called Mira and asked if we could still do the movie. She said, 'Okay, what do you think about being pregnant in the film?' And I said, 'Well, I'm four weeks pregnant so we'd better get going!' So we did, and she was a great sport about it. She said she thought it actually would help the story."

Witherspoon's condition didn't exempt her from any of the movie's more challenging sequences, including a Bollywood-style dance number. "I went into the rehearsal room and [these] gorgeous, slender women come out and start writhing around," she recalls. "And I'm like, 'Okay, Mira, what do you want me to do?' And she said, 'That's what you're going to do.' I said, 'Mira, how am I going to do that?' She said, 'Darling, you're going to do it and I know it's going to be fabulous.' So every Saturday, I would go in and rehearse. We tried to film the scene as early on as we could, so my pregnancy couldn't show so much. Some of it was really hard to do, but it was really fun."

Vanity Fair is clearly being positioned as one of the fall's first Oscar contenders, but Witherspoon claims she isn't thinking that far ahead. "I'd love to see Mira be nominated because she certainly deserves it. Knowing how much money she had to make the film and looking at the final product, it is astonishing what she was capable of."

And what about Reese's own work? "It's not something I really think about," she says. "I know it sounds trite, but honestly, I'm so happy with what my life is, I can't imagine having any more. I'm very happy to be a member of the Academy and I'd love to be honored by them. But do I expect it? No." Spoken like an awards-season pro.