if (document.images) {
  var home_off = new Image(); home_off.src = "images/nav/home-0.gif";
  var home_on = new Image(); home_on.src = "images/nav/home-1.gif";
  var products_off = new Image(); products_off.src = "images/nav/products-0.gif";
  var products_on = new Image(); products_on.src = "images/nav/products-1.gif";
  var about_us_off = new Image(); about_us_off.src = "images/nav/about_us-0.gif";
  var about_us_on = new Image(); about_us_on.src = "images/nav/about_us-1.gif";
  var contact_off = new Image(); contact_off.src = "images/nav/contact-0.gif";
  var contact_on = new Image(); contact_on.src = "images/nav/contact-1.gif";
  var order_off = new Image(); order_off.src = "images/nav/order-0.gif";
  var order_on = new Image(); order_on.src = "images/nav/order-1.gif";
  var product_list_off = new Image(); product_list_off.src = "images/nav/product_list-0.gif";
  var product_list_on = new Image(); product_list_on.src = "images/nav/product_list-1.gif";
}

function actMenuItem(imgName) { act(imgName); }
function inactMenuItem(imgName) { inact(imgName); }

function act(imgName) {
  if (document.images)
    document.images[imgName].src = eval(imgName + "_on.src");
}
function inact(imgName) {
  if (document.images)
    document.images[imgName].src = eval(imgName + "_off.src");
}