if (document.images) {

  image11on = new Image();
  image11on.src = "img/navabout_1on.gif";
  image12on = new Image();
  image12on.src = "img/navabout_2on.gif";
  image13on = new Image();
  image13on.src = "img/navabout_3on.gif";
  image14on = new Image();
  image14on.src = "img/navabout_4on.gif";
  image15on = new Image();
  image15on.src = "img/navabout_5on.gif";
  
  image11off = new Image();
  image11off.src = "img/navabout_1off.gif";
  image12off = new Image();
  image12off.src = "img/navabout_2off.gif";
  image13off = new Image();
  image13off.src = "img/navabout_3off.gif";
  image14off = new Image();
  image14off.src = "img/navabout_4off.gif";
  image15off = new Image();
  image15off.src = "img/navabout_5off.gif";
  
}

function changeImages() {
  if (document.images) {
    for (var i=0; i<changeImages.arguments.length; i+=2) {
      document[changeImages.arguments[i]].src = eval(changeImages.arguments[i+1] + ".src");
    }
  }
}