So you just saw Diane Kruger in ''Troy'' and suddenly have a hankering to dress like the lovely Helen. (Body-skimming garments are so flattering!) Prepare to launch your own thousand ships: In the greatest retro turn since Baby donned those knee-length shorts and Keds in ''Dirty Dancing,'' fashion has taken note of ''Troy''-inspired chic, leading the likes of Jennifer Lopez (in Michael Kors), Angelina Jolie (in Marc Bouwer), and Liv Tyler (in Marc Jacobs) to grace the red carpet in gowns modeled on the old-school frocks of ancient Greece and Rome.
Why the neoclassicism? ''It's more modern-day Grecian and very sexy,'' observes stylist Rachel Zoe, who put Jennifer Garner in a drapey one-shouldered Valentino at the Oscars. ''After a couple of seasons of very clean, minimalist looks, you go back to something more romantic. It's just the cycle of fashion.''
Even for the guys. ''I'm in, I'm all for it,'' says Brad Pitt of the man skirts he wore in ''Troy.'' ''I predict it's our future.'' But with graduation season approaching, any would-be ''Animal House''rs should reject one bit of the anachronism: Please don't forgo the undies.