funny - to start with I though I will definitely want to find out! Now I'm not sure. 2 reasons:
1. They sometimes get it wrong! I think this would be horrible if I was sure that I'm having a girl, bought all the pink stuff, chose girly name, dreamt about my little daughter all the time and then would have a boy after all! I mean I'm not bothered either way, just I don't want to get too used to the idea of having a daughter or a son and then be disappointed.
2. Currently we are having lots of fun with my husband choosing names for both sexes, thinking of how he or she could look, what they might do when they grow up, etc. We are preparing for both, girl and boy, and it's double fun. If I knew for definite who I'm gonna have, half of the fun would be taken away.
that's it. Personally I don't really understand the 'surprise' thing. I like surprise presents on Christmas, but the 'surprise' feeling doesn't feel very appropriate to me for having a baby. But that's a personal thing, of course.