I have 3 boys and did absolutely everything I could to get a girl (and I mean EVERYTHING over the course of 18 months)....it wasn't until we gave up trying so hard that I fell pregnant and found out 2 weeks ago that we are expecting a little girl. I agree with Arimeh though, its just a case of chance really. 50/50. However if you are really interested in reading up, there is a fantastic website that was very useful to me and some great people on there going through the same thing. Just google 'in gender'

Best of luck getting your little princess. Its the best feeling in the world.