var lgObj;

if (navigator.language) // Standard-DOM
{
  lgObj = navigator.language;
}
else if (navigator.browserLanguage) // Extrawurst fuer IE
{
  lgObj = navigator.browserLanguage;
}


var s = window.location.search;

if (lgObj.indexOf("en") > -1 && s.indexOf("L=") == -1 )
{
  document.location.href = "http://www.interlab.net/?L=1";
}