if (document.images) {
	id = document.getElementByName;
}

function On(id) {
  if (document.images) {
    document.images[id].src = "img/menu/" + id + "2" + ".gif";
  }
}
function Off(id) {
  if (document.images) {
    document.images[id].src = "img/menu/" + id + "1" + ".gif";
  }
}