$(document).ready(function(){
  window.setInterval('slideshow()', 2000);
});

function slideshow() {
  $speed = 1000;

  if ($("#currentpic").next().attr("src") == undefined){
    $("#slideshow img:first").attr("id","nextpic");
  }
  $("#currentpic").next().attr("id", "nextpic");
  $("#currentpic").fadeOut($speed, function() {
      $("#nextpic").fadeIn($speed, function() {
          $("#currentpic").attr("id", "");
          $(this).attr("id", "currentpic");
      });
      $.cookie('current_slide', $("#nextpic").attr("src"));
  });
}