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

if (browser) {
  if (document.images) {

    // top normal image
    tnrm01 = new Image();
    tnrm01.src = "images/tnrm01.jpg";
    tnrm02 = new Image();
    tnrm02.src = "images/tnrm02.jpg";
    tnrm03 = new Image();
    tnrm03.src = "images/tnrm03.jpg";
    tnrm04 = new Image();
    tnrm04.src = "images/tnrm04.jpg";
    tnrm05 = new Image();
    tnrm05.src = "images/tnrm05.jpg";
    tnrm06 = new Image();
    tnrm06.src = "images/tnrm06.jpg";

    // top hover image
    thov01 = new Image();
    thov01.src = "images/thov01.jpg";
    thov02 = new Image();
    thov02.src = "images/thov02.jpg";
    thov03 = new Image();
    thov03.src = "images/thov03.jpg";
    thov04 = new Image();
    thov04.src = "images/thov04.jpg";
    thov05 = new Image();
    thov05.src = "images/thov05.jpg";
    thov06 = new Image();
    thov06.src = "images/thov06.jpg";

  }
}

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