Questa è la pagina e va su IE7, Opera9, Firefox2
di più, non so 
 
ciao 
 
	codice:
	<%@ Page Language="VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim ajax As String = RequestParams("ajax")
        If ajax = "1" Then
            Response.Write("Ciao, Mondo")
            Response.End()
        End If
    End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Pagina senza titolo</title>
    <script language="javascript" type="text/javascript">
// <!CDATA[
function simple_ajax(url,target) {
	  var ajax = null;
	  if (window.XMLHttpRequest) {
		ajax = new XMLHttpRequest();
	  } else if (window.ActiveXObject) {
		ajax = new ActiveXObject("Microsoft.XMLHTTP");
	  }
  if(ajax) {
    ajax.open("get", url, true);
    ajax.setRequestHeader("connection", "close");
	
    ajax.onreadystatechange = function() {
	      if(ajax.readyState == 4 && ajax.status == 200) {
               document.getElementById(target).innerHTML = ajax.responseText;
         } 
    }
    ajax.send(null);
  }
   
} 
// ]]>
    </script>
</head>
<body>
    <form id="form1" runat="server">
        <input type="button" onclick="simple_ajax('a.aspx?ajax=1', 'tar')" value="carica ajax" />
        <div id="tar"></div>
    </form>
</body>
</html>