function findImage(){
	var images, i;
	images = document.getElementsByTagName('img');
	for ( i = 0; i < images.length; i++ ){
		if (/rollover/.test(images[i].className)){
			images[i].onmouseover = function(){rollImage(this);};
			images[i].onmouseout = function(){rollImage(this);};
		}
	}
}

function rollImage(roll){
	var src, oversrc;
	src = roll.src;
	if(/_off/.test(src)){
		oversrc = src.replace('_off','_hover');
	}
	else{
		oversrc = src.replace('_hover','_off');
	}
	roll.src = oversrc;
}

addLoadEvent(findImage);