// if the cookie doesn't exist, set it
if ($.cookie('new_visitor') == null) {
  $.cookie('new_visitor', 'YES', { expires: 5 });

  $(window).load(function() {

    Shadowbox.open({
      player: 'iframe',
      content: '/themes/frontend/blackdiamond/modules/blackdiamond/newvisitor/index.php',
      height: 465,
      width: 708
    });

  });
}