function preloadImages() {
//Usage: preloadImages('image 1 URL', 'image 2 URL', 'image 3 URL', ...);
  var img;
  
  if (document.images) {
    for(arg=0;arg<preloadImages.arguments.length;arg++) {
      img = new Image();
      img.src = preloadImages.arguments[arg];
    }
	preloadFlag = true;
  }
}

function changeImages() {
//Usage: changeImages('object 1', 'new image 1 URL', 'object 2', ...);
	if (document.images) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
		}
	}
}