Countdown

<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>TITULO DA PAGINA</title>

<script type="text/javascript">
window.onload=function() {
function countdown() {
if ( typeof countdown.counter == 'undefined' ) {
    countdown.counter = 5; // inicio
    }
if(countdown.counter > 0) {
    document.getElementById('count').innerHTML = countdown.counter--;
    setTimeout(countdown, 1000);
    }
else {
    location.href = 'http://XPTO.PT/';
    }
}
countdown();
};
</script>

</head>
<body>
<h2>Vai ser redireccionado em <span id="count"></span> segundos</h2>.
</body>
</html>