Mine

/** XHConn - Simple XMLHTTP Interface - bfults@gmail.com - 2005-04-08        **
 ** Code licensed under Creative Commons Attribution-ShareAlike License      **
 ** http://creativecommons.org/licenses/by-sa/2.0/                           **/


function XHConn()
{
  var xmlhttp, bComplete = false;
  try { xmlhttp = new ActiveXObject("Msxml2.XMLHTTP"); }
  catch (e) { try { xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); }
  catch (e) { try { xmlhttp = new XMLHttpRequest(); }
  catch (e) { xmlhttp = false; }}}
  if (!xmlhttp) return null;
  this.connect = function(sURL, sMethod, sVars, fnDone)
  {
    if (!xmlhttp) return false;
    bComplete = false;
    sMethod = sMethod.toUpperCase();

    try {
      if (sMethod == "GET")
      {
        xmlhttp.open(sMethod, sURL+"?"+sVars, true);
        sVars = "";
      }
      else
      {
        xmlhttp.open(sMethod, sURL, true);
        xmlhttp.setRequestHeader("Method", "POST "+sURL+" HTTP/1.1");
        xmlhttp.setRequestHeader("Content-Type",
          "application/x-www-form-urlencoded");
      }
      xmlhttp.onreadystatechange = function(){
      	
        if (xmlhttp.readyState == 4 && !bComplete)
        {  
      showpreloader(0);
          bComplete = true; 
          fnDone(xmlhttp);
	
        }

      };
      xmlhttp.send(sVars);
    }
    catch(z) {  return false; }
    return true; 
  };
  return this;
}














<script>
function showpreloader(what) {
	if (what == 1) { 
document.getElementById('contentform').style.display='block';
document.getElementById('preloader').style.display='none';
	} else {
	document.getElementById('contentform').style.display='none';
document.getElementById('preloader').style.display='block';	
		
	}
	
	} 
	</script>

<div id="preloader" style="display:block;">loading..........</div>
<div id="contentform" style="display:none;">content</div>