ho provato , non va , come devo fare?

<%@LANGUAGE="VBSCRIPT" CODEPAGE="1252"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Documento senza titolo</title>

<script type="text/javascript" language="javascript" src="script/prototype-1.6.0.3.js" ></script>

<script type="text/javascript">
Event.Observe(window, "load", function(){
new Ajax.PeriodicalUpdater('ciao', 'prova.asp', { method: 'get', frequency: 3, decay: 2 });
})
</script>

</head>

<body>
<div align="center" id="ciao"><%Response.Write Now()%></div>
</body>
</html>