browser = (((navigator.appName == "Netscape") && (parseInt(navigator.appVersion) >= 3 )) ||
          ((navigator.appName == "Microsoft Internet Explorer") && (parseInt(navigator.appVersion) >= 4 )));

if (browser) {
  if (document.images)
  {
    // nav normal image
    nrm01 = new Image();
    nrm01.src = "images/navnrm01.jpg";
    nrm02 = new Image();
    nrm02.src = "images/navnrm02.jpg";
    nrm03 = new Image();
    nrm03.src = "images/navnrm03.jpg";

    // nav hover image
    hov01 = new Image();
    hov01.src = "images/navhov01.jpg";
    hov02 = new Image();
    hov02.src = "images/navhov02.jpg";
    hov03 = new Image();
    hov03.src = "images/navhov03.jpg";
  }
}

function swapImg(imgDocID,imgObjName) {
  document.images[imgDocID].src = eval(imgObjName + ".src");
}