//------------------------------------------
// create object
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;
  }//else
}//function