function go_prefcenter() {
    if( validate() ) {
	window.location="http://www.fidelity-adviser.com/signup/signup.py/signup?email=" + document.getElementById( 'username' ).value;
    }
}

function validate() {
    var emailre = /.+@.+\..+/;
    if( document.getElementById( 'username' ).value.match( emailre ) ) {
        return true;
    }
    alert( 'Form submission not complete.\nPlease enter a proper email address.' );
    return false;
}