function GetXmlHttpObject() {
    var xmlHttp=null;
    try  {
        // Firefox, Opera 8.0+, Safari
        xmlHttp=new XMLHttpRequest();
    }
    catch (e) {
        // Internet Explorer
        try {
            xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
        }  catch (e) {
            xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
        }
    }

    return xmlHttp;
}