$.fn.preload = function() {
    this.each(function(){
        $('<img/>')[0].src = this;
    });
}

$(document).ready(function(){
	$(['/wp-content/themes/bts/images/nav/about-over.png','/wp-content/themes/bts/images/nav/pray-over.png','/wp-content/themes/bts/images/nav/media-over.png','/wp-content/themes/bts/images/nav/store-over.png']).preload();
	$("#nav > li").hover(
		function(){
			var icon = $(this).find("img").attr("src");
			var orig = icon.split("-up.")[0];
			$(this).find("img").attr({src: orig + "-over.png"});
		}, 
		function(){
			var icon = $(this).find("img").attr("src");
			var orig = icon.split("-over.")[0];
			$(this).find("img").attr({src: orig + "-up.png"});
		});
});