function preloadImages() {
  if (document.images) {
    var imgFiles = preloadImages.arguments;
    if (document.preloadArray==null) 
      document.preloadArray = new Array();
    var i = document.preloadArray.length;
    with (document) for (var j=0; j<imgFiles.length; j++){
      preloadArray[i] = new Image;
      preloadArray[i++].src = imgFiles[j];
    }
  }
}

function swapImgRestore() {
  if (document.swapImgData != null)
    for (var i=0; i<(document.swapImgData.length-1); i+=2)
      document.swapImgData[i].src = document.swapImgData[i+1];
}

function swapImage() {
  var i;
  var j=0;
  var objStr;
  var obj;
  var swapArray=new Array;
  var oldArray=document.swapImgData;

  for (i=0; i < (swapImage.arguments.length-1); i+=2) {
    objStr = swapImage.arguments[i];
    obj = eval(objStr);
    swapArray[j++] = obj;
    swapArray[j++] = (oldArray==null || oldArray[j-1]!=obj)?obj.src:oldArray[j];
    obj.src = swapImage.arguments[i+1];
  }
  document.swapImgData = swapArray; //used for restore
}