$(function () {
      var tabcontainers = $('#box_unten .content');
      tabcontainers.hide().filter(':first').show();
      
      $('#tabNavigation a').click(function(){
         tabcontainers.hide().filter(this.hash).show();
         //console.log(this);
         $('#tabNavigation a').removeClass('selected');
         $(this).addClass('selected');
         return false;
      }).filter(':first').click();
  });