function Rollover(){

	var images	=	document.getElementsByTagName("img");
	
	for(var i = 0; i < images.length; i++){
	
		if(rollover = images[i].getAttribute("rollover")){
		
			this.add(images[i], rollover);
		
		}
	
	}

}

Rollover.prototype.add		=	function(image, image_url_over){
	
	var preload_image	=	new Image();
	preload_image.src	=	image_url;
	
	var image_url		=	image.src;
	
	image.onmouseout	=	function(){ image.src = image_url; }
	image.onmouseover	=	function(){ image.src = image_url_over; }

}