Finding out if it's a boy or girl

I have one child from a previous relationship. I had to know the gender of the baby as soon as possible (Alexis Marie was born in 2009). With this pregnancy though, I want the gender to be a surprise until we get to meet him/her. My husband and I have a boy and a girl name picked out, both of which we agree on, but because this is his first child, I feel almost selfish for wanting to keep it a surprise. Any suggestions?