function goAjax(url, metodo, modo, tagRetorno, parametros) {
        document.getElementById(tagRetorno).innerHTML='<div align="center" class="carregando"><img src="../images/carregando.gif"><br /><br />carregando...</div>'

            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) {
                    retorno=xmlhttp.responseText
                    document.getElementById(tagRetorno).innerHTML=retorno
                    findScript(retorno)
                }
            }
            if(metodo == "GET") {
                xmlhttp.send(null);
            } else {        
                xmlhttp.send(parametros);
            }
}










function createXMLHTTP() 
            {
                        var ajax;
                        try 
                        {
                                   ajax = new ActiveXObject("Microsoft.XMLHTTP");
                        } 
                        catch(e) 
                        {
                                   try 
                                   {
                                               ajax = new ActiveXObject("Msxml2.XMLHTTP");
                                               alert(ajax);
                                   }
                                   catch(ex) 
                                   {
                                               try 
                                               {
                                                           ajax = new XMLHttpRequest();
                                               }
                                               catch(exc) 
                                               {
                                                            alert("Esse browser não tem recursos para uso do Ajax");
                                                            ajax = null;
                                               }
                                   }
                                   return ajax;
                        }
            
            
                           var arrSignatures = ["MSXML2.XMLHTTP.5.0", "MSXML2.XMLHTTP.4.0",
                                                                                      "MSXML2.XMLHTTP.3.0", "MSXML2.XMLHTTP",
                                                                                      "Microsoft.XMLHTTP"];
                           for (var i=0; i < arrSignatures.length; i++) 
                           {
                                               try 
                                               {
                                                           var oRequest = new ActiveXObject(arrSignatures[i]);
                                                           return oRequest;
                                               } 
                                               catch (oError) 
                                               {
                                       }
                           }
                        
                                      throw new Error("MSXML is not installed on your system.");
            }