var req;

function validarDados(email, acao) {

        if(window.XMLHttpRequest) {
                req     = new XMLHttpRequest();
        }
        // Internet Explorer
        else if(window.ActiveXObject) {
                req = new ActiveXObject("Microsoft.XMLHTTP");
        }
        var url = "informativo.php?Email="+email+"&Acao="+acao;
        req.open("Get", url, true); 
        req.onreadystatechange = function() {
                if(req.readyState == 1) {
                        document.getElementById('resposta').innerHTML = '<center><img src="img/c_carregando.gif"></center>';
                }
                if(req.readyState == 4 && req.status == 200) {   
                        var resposta = req.responseText;
                        document.getElementById('resposta').innerHTML = resposta;
                }
        }
        req.send(null);
}