[jQuery] Submit event

[jQuery] Submit event


Hi There,
I could use some jquery help here. This probably something very
simple that I'm missing. I started using jquery a few weeks ago so
please bear with me.
In a nut shell, when a user submits the form (form id="register"), I
want it check to make sure they have selected a radio button
(class="amount"). If they forgot, I want it turn the #billing id (<h2
id="billing>) red. I have server side validation working using PHP.
This is more of a visual indicator. I'm using the validate.js plug-in
and jquery 1.2.1. Any help would be great!
$(document).ready(function() {
    $("#register").submit( function() {
        checkRadio();
    });
    function checkRadio() {
        $('input.amount').each(function() {
            if ($('input:unchecked')) {
                $("#billing").css('color', '#658300').show();
                return true;
            } else {
                $("#billing").css('color', '#C60006').show();
                return false;
            }
        });
    //close function
    };
});