function goAjax(url, metodo, modo, tagRetorno, parametros) {
	
try{
    xmlhttp = new XMLHttpRequest();
}catch(ee){
    try{
        xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
    }catch(e){
        try{
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
        }catch(E){
            xmlhttp = false;
        }
    }
}

            if(metodo == "GET") {
                xmlhttp.open("GET", url, modo);
            } else {        
                xmlhttp.open("POST", url, modo);
                xmlhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded; charset=iso-8859-1");
                xmlhttp.setRequestHeader("Cache-Control", "no-store, no-cache, must-revalidate");
                xmlhttp.setRequestHeader("Cache-Control", "post-check=0, pre-check=0");
                xmlhttp.setRequestHeader("Pragma", "no-cache");
            }    
            
            xmlhttp.onreadystatechange = function() {
                if(xmlhttp.readyState == 4) {
                    var retorno=unescape(xmlhttp.responseText);
					var conteudoX = document.getElementById(tagRetorno);
                    conteudoX.innerHTML=retorno; 
                }
            }
            if(metodo == "GET") {
                xmlhttp.send(null);
            } else {        
                xmlhttp.send(parametros);
            }
}