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Celebrities bundled up on a frigid New York night for a preview screening of "Blue Valentine." But the film's star, Michelle Williams, told us she chose a flirty white Dior minidress... because of her haircut?

Her new pixie cut may have earned a universal thumbs-up, but the actress said it means she has to rethink her outfits. "You can't wear (things like) a blazer anymore, which rules out half my wardrobe," she laughed. "It starts to look too tough!"

Snow flurried outside the screening sponsored by the Cinema Society and Piaget, attended by guests like Joan Rivers, Jamie-Lynn Sigler, Gabourey Sidibe and the film's director, Derek Cianfrance. Rivers was characteristically frank about her animal insulation.

"They all died a long time ago, and if they died, they should not have died in vain," she declared of the not one, but two furs she arrived wearing. "When it's cold, you understand the Eskimos!"

Victoria's Secret Angel Alessandra Ambrosio, sporting Cavalli sequins and a leather Elise Øverland trench, had her own tactics for braving the cold. "Warm dresses, cashmere, something sparkling! I definitely dress more festive during the holidays!"

Both Williams and co-star Ryan Gosling received Golden Globe nominations this morning for the film. It follows the couple through two stages of their lives: young and in love, and older and, well, not quite as in love.

The film may get bluer as it goes along, but Ambrosio shared with us a happier memory.

"The best Valentine I ever had was when I was pregnant and my fiancé took me to have chocolate fondue. As pregnant as I was, all I wanted to do was eat!" she laughed. "Another time, he played all the songs from Pearl Jam, which is my favorite band. He serenaded me!"