Scarlett Johansson arrives for the premiere of the film "The Black Dahlia" held at the Academy of Motion Pictures Arts and Sciences in Beverly Hills, California September 6, 2006.

NEW YORK - Scarlett Johansson struts her stuff in cleavage-baring dresses on the red carpet, but in real life, she'd rather remain a mystery.

"I can't stand those articles where people spill their life story," Johansson says in the October issue of InStyle magazine, on newsstands Friday. "After a while I feel like I know more about them than their best friend does - and that's weird. It's better when you don't know everything."

The 21-year-old actress, whose screen credits include "Lost in Translation" and "Match Point," plays a former prostitute in "The Black Dahlia," opposite Hilary Swank and Josh Hartnett.

Johansson says: "Do I ever get nervous about this, right now, being the pinnacle of my career? Yeah, I do. At the end of (filming) every movie I think, `Wow - this is the last one! Nice working with you.'"

She's more confident about her hourglass figure. "I'm curvy - I'm never going to be 5'11' and 120 pounds. But I feel lucky to have what I've got."

And, given the chance, she'd like to trade lives with

President Bush. "Whose life would I like to step into for the day? The president's. I could probably get some things done in the Oval Office."