Which Ayn Rand Book Should I Read?

Last weekend, I read a very provocative piece in the NY Times that got me curious about Ayn Rand. While I’ve heard lots about Ms. Rand and her objectivist teachings, I have to confess I’ve never read her work. So, I’ve decided it’s time to take the plunge and dig into one of her books. Which of her books is the best introduction to her style and philosophy? If I’m only going to read one (and they’re very long, so I’ll probably only read one), which should it be? Thanks!