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) {
    id1_over = newImage("nav/1-over.jpg");
    id2_over = newImage("nav/2-over.jpg");
    id3_over = newImage("nav/3-over.jpg");
    id4_over = newImage("nav/4-over.jpg");
    id5_over = newImage("nav/5-over.jpg");
    id6_over = newImage("nav/6-over.jpg");
    id7_over = newImage("nav/7-over.jpg");
    id8_over = newImage("nav/8-over.jpg");
    id10_over = newImage("nav/adventuresover.gif");
    id11_over = newImage("nav/2-over.gif");
    id12_over = newImage("nav/investmentover.gif");
    id13_over = newImage("nav/motorcycleover.gif");
    id14_over = newImage("nav/travelover.gif");
    preloadFlag = true;
  }
}