aRolloverImg = new Array();
aRolloverCnt = 0;
(function($) {
	$.fn.rollover = function(postfix) {
		postfix = (postfix != null) ? postfix : '_on';
		return jQuery.each(this.not('[src*="'+ postfix +'."]'), function() {
			var img = $(this);
			var src = img.attr('src');
			var src_on = src.substr(0, src.lastIndexOf('.')) + postfix + src.substring(src.lastIndexOf('.'));
			aRolloverImg[aRolloverCnt] = new Image();
			aRolloverImg[aRolloverCnt].src = src_on;
			img.attr('src_on', src_on);
			img.attr('src_off', src);
			img.hover(
				function() { img.attr('src', img.attr('src_on')); },
				function() { img.attr('src', img.attr('src_off')); }
			);
			aRolloverCnt++;
		});
	};
})(jQuery);