function simplePreload()
{ 
  var args = simplePreload.arguments;
  document.imageArray = new Array(args.length);
  for(var i=0; i<args.length; i++)
  {
    document.imageArray[i] = new Image;
    document.imageArray[i].src = args[i];
  }
}

function switchImage(imgName, onOff) {
    imgDir = '/images/donatenow/';
    if (document.images) {
        if (onOff == "on") {
            document.images[imgName].src = imgDir + imgName + "_on.jpg";
        } else {
            document.images[imgName].src = imgDir + imgName + "_off.jpg";
        }
    }
}

document.onLoad = simplePreload('/images/donatenow_on.jpg');