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

$.preloadImages("/media/image/menu-about-off-out.jpg","/media/image/menu-about-off-over.jpg","/media/image/menu-about-on-out.jpg","/media/image/menu-about-on-over.jpg");
$.preloadImages("/media/image/menu-atelier-off-out.jpg","/media/image/menu-atelier-off-over.jpg","/media/image/menu-atelier-on-out.jpg","/media/image/menu-atelier-on-over.jpg");
$.preloadImages("/media/image/menu-illustration-off-out.jpg","/media/image/menu-illustration-off-over.jpg","/media/image/menu-illustration-on-out.jpg","/media/image/menu-illustration-on-over.jpg");
$.preloadImages("/media/image/menu-web-off-out.jpg","/media/image/menu-web-off-over.jpg","/media/image/menu-web-on-out.jpg","/media/image/menu-web-on-over.jpg");
$.preloadImages("/media/image/menu-print-off-out.jpg","/media/image/menu-print-off-over.jpg","/media/image/menu-print-on-out.jpg","/media/image/menu-print-on-over.jpg");

function swapPopup(script,portfolio,visuel) {
 var html = $.ajax({
  url: script,
  data: "id_portfolio="+portfolio+"&id_visuel="+visuel,
	async: false	
 }).responseText;
 $("div#myPopup").replaceWith(html);
}