IE5 = (navigator.userAgent.indexOf("MSIE 5") > 0) ? 1 : 0;

if (document.all && !IE5) {  //overload document.getElementById for IE4
  document.getElementById = function (name) {
    return document.all(name);
  }
}

function imageOn(item) {
  if (document.images && loaded) {
    imgOn = eval(item+ "_on.src");
    document.getElementById(item).src = imgOn;
  }
}

function imageOff(item) {
  if (document.images && loaded) {
    imgOn = eval(item+ "_off.src");
    document.getElementById(item).src = imgOn;
  }
}