function makePOSTRequest(url, parameters){
  http_request = false;
  if (window.XMLHttpRequest){ 
	 // Mozilla, Safari,...
	 http_request = new XMLHttpRequest();
	 if (http_request.overrideMimeType){
		// set type accordingly to anticipated content type
		//http_request.overrideMimeType('text/xml');
		http_request.overrideMimeType('text/html');
	 }
  }else if(window.ActiveXObject){ 
	// Internet Explorer
	 try{
		http_request = new ActiveXObject("Msxml2.XMLHTTP");
	 }catch(e){
		try{
		   http_request = new ActiveXObject("Microsoft.XMLHTTP");
		}catch(e){}
	 }
  }
  
  if(!http_request){
	 alert('Cannot create XMLHTTP instance');
	 return false;
  }
  
  http_request.onreadystatechange = alertContents;
  http_request.open('POST', url, true);
  http_request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
  http_request.setRequestHeader("Content-length", parameters.length);
  http_request.setRequestHeader("Connection", "close");
  http_request.send(parameters);
}