function llamadaAJAX(origenDatosURL, divDestino)
{ 

   xmlhttp=null 
   // código para Mozilla 
   if (window.XMLHttpRequest){ 
     xmlhttp=new XMLHttpRequest() 
   } 
   // ódigo para IE 
   else if (window.ActiveXObject){ 
     xmlhttp=new ActiveXObject("Microsoft.XMLHTTP") 
   } 
   if (xmlhttp!=null)
	{ 
	    xmlhttp.open("GET", origenDatosURL, false); 
		//xmlhttp.setRequestHeader('content-type', 'text/xml');		
		xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
		xmlhttp.setRequestHeader("Accept-Charset", "iso-8859-1");		
		//xmlhttp.setRequestHeader("If-Modified-Since", "Sat, 1 Jan 2000 00:00:00 GMT" );
		//xmlhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
	    xmlhttp.send(null); 
    	document.getElementById(divDestino).innerHTML = xmlhttp.responseText; 
	}       
}