function doMenu() {
  if (location.href.match(/\/products\//)) {
    d=document.getElementById('main_products');
    d.src="http://espanol.alpine-usa.com/img/alpine/ES_48618.jpg";
  }
  if (location.href.match(/\/company\//)) {
    d=document.getElementById('main_company');
    d.src="http://espanol.alpine-usa.com/img/alpine/ES_48624.jpg";
  }
  if (location.href.match(/\/fun\//)){
    d=document.getElementById('main_fun');
    d.src="http://espanol.alpine-usa.com/img/alpine/ES_48622.jpg";
  }
  if (location.href.match(/\/support\//)) {
    d=document.getElementById('main_support');
    d.src="http://espanol.alpine-usa.com/img/alpine/ES_48620.jpg";
  }
}

doMenu();