var images = new Array(
  "bilder/1902305text.jpg",
  "bilder/5858335text.jpg",
  "bilder/8204786text.jpg",
  "bilder/9104346text.jpg"
);

var index = Math.floor(Math.random() * images.length);

$(window).load(function() {
  $('#rotator').html('<img src="'+images[index]+'" alt="" border="0" width="750" height="500" />');
  index = (index + 1) % images.length;

  setInterval(function() {
    $('#rotator img').fadeOut(1000, function(e) {
        $('#rotator').html('<img src="'+images[index]+'" style="display: none" alt="" border="0" width="750" height="500" />');
        $('#rotator img').fadeIn(1000);
        index = (index + 1) % images.length;
      });
  }, 7000);
});