function newImage(arg) {
     if (document.images) {
          rslt = new Image();
          rslt.src = arg;
          return rslt;
     }
}

function changeImages() {
     if (document.images && (preloadFlag == true)) {
          for (var i=0; i<changeImages.arguments.length; i+=2) {
               document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
          }
     }
}

var preloadFlag = false;
function preloadImages() {
     if (document.images) {
		nav_prodserv_over = newImage("/_assets/images/nav_prodserv_over.gif");
		nav_patientinfo_over = newImage("/_assets/images/nav_patientinfo_over.gif");
		nav_news_over = newImage("/_assets/images/nav_news_over.gif");
		nav_invrel_over = newImage("/_assets/images/nav_invrel_over.gif");
		nav_empopp_over = newImage("/_assets/images/nav_empopp_over.gif");
		nav_diseasemgm_over = newImage("/_assets/images/nav_diseasemgm_over.gif");
		nav_cusvisitors_over = newImage("/_assets/images/nav_cusvisitors_over.gif");
        preloadFlag = true;
     }
}