function go(option) {
  var link;
  switch (option.value) {
  case "1":
    link = "http://www.netlands.de/internetagentur.html"; 
    break;
  case "2":
    link = "http://www.netlands.de/internetagentur.html"; 
    break;
  case "3":
     link = "http://www.netlands.de/internetagentur.html";
    break;
  case "4":
     link = "http://www.netlands.de/internetagentur.html";
    break;
  default:
    return null;
    break;
  }
  document.location.href=link; 
}