jQuery.preloadImages = function()
{
  for(var i = 0; i<arguments.length; i++)
  {
    jQuery("<img>").attr("src", arguments[i]);
  }
}

$.preloadImages("/images/nav_windows-2.gif", "/images/nav_doors-2.gif", "/images/nav_green-2.gif", "/images/nav_warranty-2.gif", "/images/nav_safeharbor-2.gif", "/images/nav_vipro-2.gif", "/images/nav_contact-2.gif");

$(document).ready(function() {
	$("div#top-nav ul li").hover(
		function() { 
			
			$image = $(this).find("img").attr("src");
			$image = $image.substring(0,$image.length-6) + "-2.gif";

			$(this).find("img").attr("src",$image);
			$(this).addClass("over");
		},
		function() {
			$image = $(this).find("img").attr("src");
			$image = $image.substring(0,$image.length-6) + "-1.gif";
			
			$(this).find("img").attr("src",$image);
			$(this).removeClass("over");
		}
	);
});