function getDataServer(url, vars)
{
     var xml = null;
     try
	 {
         xml = new ActiveXObject("Microsoft.XMLHTTP");
     }catch(expeption)
	   {
         xml = new XMLHttpRequest();
       }
     xml.open("GET",url + vars, false);
     xml.send(null);
     if(xml.status == 404) alert("Url no valida");
     return xml.responseText;
}