var xmlhttp = createXmlHttpRequestObject();

function createXmlHttpRequestObject(){
	var xmlhttp;
  try{//other browers plus ie 7
    xmlhttp = new XMLHttpRequest();
  }//try
  catch(e){//older ie browsers
  var xmlhttpVersions = new Array("MSXML2.XMLHTTP.6.0",
							 "MSXML2.XMLHTTP.5.0",
							 "MSXML2.XMLHTTP.4.0",
							 "MSXML2.XMLHTTP.3.0",
							 "MSXML2.XMLHTTP",
							 "Microsoft.XMLHTTP");
  for(var i = 0; i<xmlhttpVersions.length && !xmlhttp; i++){//step through xmlhttpVersions array
	  try{
   var xmlhttp = new ActiveXObject(xmlhttpVersions[i]);
	  }//try
	  catch(e){}
  }//for
  }//catch(e)
  if(!xmlhttp){
  alert('There has been an error creating the XMLHTTPRequest object.');
    }else{
    return xmlhttp;
	}
}