jQuery(document).ready(function(){
         jQuery('#a').hover(
            function(){ // Change the input image's source when we "roll on"
                 jQuery(this).attr({ src:'http://www.dentalplancards.com/wp-content/themes/acosminbiz/images/plansearchbutton-hover.png'});
            },
            function(){ // Change the input image's source back to the default on "roll off"
                jQuery(this).attr({ src:'http://www.dentalplancards.com/wp-content/themes/acosminbiz/images/plansearchbutton.png' });             }
        );
    });