// Function to preload rollover images for non IE
        $.fn.preload = function () { 
            this.each(function () {
                $('<img/>')[0].src = this;
            });
        }
        // Usage:
        $(['images/layout/vw_on.png', 'images/layout/services_on.png', 'images/layout/whyus_on.png', 'images/layout/contactus_on.png', 'images/layout/footer/email_on.png', 'images/layout/footer/twitter_on.png', 'images/layout/footer/faceb_on.png']).preload();

        //Function to rollover images
        $(document).ready(function () {
            $("img.rollover").hover(
function () {
    this.src = this.src.replace("_off", "_on");
},
function () {
    this.src = this.src.replace("_on", "_off");
});
        });