$.fn.preload = function() {
    this.each(function(){
        $('<img/>')[0].src = this;
    });
}
$('a[rel="external"]').click(function(){
	window.open(this.href);
	return false;
});
$("#nav_top li img").hover(
	function () {
		$(this).attr("src", $(this).attr("src").replace(/.jpg/, "-over.jpg"));
	},
	function () {
		$(this).attr("src", $(this).attr("src").replace(/-over.jpg/, ".jpg"));
	}
);