function browsercheck()
{
 if (navigator.appVersion.charAt(0)<'4')
 {
      // Für alle Brwoser unterhalb der Version 4
	  	  window.location.replace("pages/zualt.htm");	  
 }
   else
    {
      // Für alle Browser ab Version 4
        if (navigator.appName=='Netscape')
          {
          window.location.replace("pages/mainframe.htm");
          }
         if (navigator.appName=='Microsoft Internet Explorer')
           {
           window.location.replace("pages/index_ie.htm");						  
           }
		  if (navigator.appName!='Netscape' && navigator.appName!='Microsoft Internet Explorer')
		   {
		   window.location.replace("pages/mainframe.htm");
		   }  
    }
}