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) {
    disnav_02_over = newImage("images/disnav_02_over.gif");
    disnav_02_down = newImage("images/disnav_02_down.gif");
    disnav_03_over = newImage("images/disnav_03_over.gif");
    disnav_03_down = newImage("images/disnav_03_down.gif");
    disnav_04_over = newImage("images/disnav_04_over.gif");
    disnav_04_down = newImage("images/disnav_04_down.gif");
    disnav_05_over = newImage("images/disnav_05_over.gif");
    disnav_05_down = newImage("images/disnav_05_down.gif");
    disnav_06_over = newImage("images/disnav_06_over.gif");
    disnav_06_down = newImage("images/disnav_06_down.gif");
    disnav_07_over = newImage("images/disnav_07_over.gif");
    disnav_07_down = newImage("images/disnav_07_down.gif");
    disnav_08_over = newImage("images/disnav_08_over.gif");
    disnav_08_down = newImage("images/disnav_08_down.gif");
    disnav_09_over = newImage("images/disnav_09_over.gif");
    disnav_09_down = newImage("images/disnav_09_down.gif");
    disnav_10_over = newImage("images/disnav_10_over.gif");
    disnav_10_down = newImage("images/disnav_10_down.gif");
    preloadFlag = true;
  }
}