I don't know if you took the file out of your action on purpose or not. But your form doesn't have an action at all. It simple says
Take a look at this tutorial.
Maybe you can take some ideas from this, and apply it to your code. Looking through your script it shouldn't be too hard.
A nice Ajax contact form tutorial is over at http://tutorialzine.com/2009/09/fancy-contact-form/
They;ve gone in a little bit different of a direction than you, but it's a pretty nice script.