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) {
    home_over = newImage("images/nav/home-over.gif");
    upcome_over = newImage("images/nav/upcome-over.gif");
    gallery_over = newImage("images/nav/gallery-over.gif");
    purchase_over = newImage("images/nav/purchase-over.gif");
    workshop_over = newImage("images/nav/workshop-over.gif");
    contact_over = newImage("images/nav/contact-over.gif");
    links_over = newImage("images/nav/links-over.gif");
    preloadFlag = true;
  }
}