$(function(){
	
	// rollover
	$('.on').each(function(){
		this.originalSrc = $(this).attr('src');
		this.rolloverSrc = this.originalSrc.replace(/(\.gif|\.jpg|\.png)/, "_on$1");
	}).hover(function(){
		$(this).attr('src',this.rolloverSrc);
	},function(){
		$(this).attr('src',this.originalSrc);
	});
});