$(document).ready(function(){
	$('img.roll').bind('mouseover', function(){
		this.src = this.src.replace(/(.*)\.(jpg|gif|png)$/i, "$1-over.$2")
	});
	$('img.roll').bind('mouseout', function(){
		this.src = this.src.replace(/(.*)-over\.(jpg|gif|png)$/i, "$1.$2")
	});				
});