Windows 7小工具，http req。 GET vz。 POST

I'm developing a small gadget for our intranet and I have a small php file on our server just for first test. Now, everything is working if I'm using GET request but I would like to use POST to not have all data in URL. Unfortunately I'm not possible to get any data by POST request.

Working solution with GET:

  function ajax_getData() {   
    var error = false;
    ajax = new ActiveXObject("Msxml2.XMLHTTP");   
    ajax.open("GET", "http://server.com/index.php" + "?update&login=" + g_LOGIN + "&pass=" + g_PASS, true);
    ajax.onreadystatechange = function() { 
      if (ajax.readyState === 4) {
        if (ajax.status === 200) {   
          try {     
            $('#div0').html(ajax.responseText); 
            // do something     
          } catch (e) {  
            error = true; 
          }
        } else {
          error = true; 
        }
      } else {
      }       
      if (error) {      
        // handle error
      }  
    };  
    ajax.send(null);  
  }

index.php

echo(var_dump($_POST));

Now, my not working POST solution:

 function ajax_getData() {   
    var error = false;
    ajax = new ActiveXObject("Msxml2.XMLHTTP");   
    ajax.open("POST", "http://server.com/index.php", false); 
    //ajax.open("POST", "http://server.com/index.php", true); 
    ajax.send("update&login=" + g_LOGIN + "&pass=" + g_PASS);
    ajax.onreadystatechange = function() { 
      if (ajax.readyState === 4) {
        if (ajax.status === 200) {   
          try {     
            $('#div0').html(ajax.responseText); 
            // do something     
          } catch (e) {  
            error = true; 
          }
        } else {
          error = true; 
        }
      } else {
      }       
      if (error) {      
        // handle error
      }  
    };  
    ajax.send(null);  
  }

In case POST solution I always get from index.php only 'Array(0)'.

What about using new XMLHttpRequest() instead of new ActiveXObject("Msxml2.XMLHTTP");

From http://www.w3schools.com/ajax/ajax_xmlhttprequest_create.asp :

All modern browsers (IE7+, Firefox, Chrome, Safari, and Opera) have a built-in XMLHttpRequest object.

Syntax for creating an XMLHttpRequest object:

variable=new XMLHttpRequest();

Old versions of Internet Explorer (IE5 and IE6) uses an ActiveX Object:

variable=new ActiveXObject("Microsoft.XMLHTTP");