I use the jQuery Form Plugin for AJAX. Download it from here and insert it into the <head> section of your page. Then invoke your form by using the following script:
This script also adds a class of .hover when you rollover the submit button. Actually it will add the class ‘hover’ to any <input> tag within the form that has the class ‘button’. It also removes the ‘hover’ class when the mouse moves out of the button. This enables you to style your button using simple css.