I've heard alot about these ultrasound places that say they can tell you at 16 weeks whether you're having a boy or a girl. The one I've heard people talk about is called "Becoming Mom".

It's supposed to be ~$100. I'd do it! lol, I think it'd be hard to have someone living inside me for 20 weeks/5 months and not know! haha, I could never be team green!