meuAjax = function (){   
    try{   
        xmlhttp = new XMLHttpRequest();   
    }catch(ee){   
        try{   
            xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");   
        }catch(e){   
            try{   
                xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");   
            }catch(E){   
                xmlhttp = false;   
            }   
        }   
    }   
}