var xmlHTTP = getXMLHTTP();

if (xmlHTTP) {
    xmlHTTP.async = false;
    xmlHTTP.open('get', 'http://google.com/');
    xmlHTTP.send(null);

    if (xmlHTTP.status == 200) {
        var data = xmlHTTP.responseText;
    }
}

function getXMLHTTP()
{
    if ((typeof XMLHttpRequest) != "undefined") {
        /* XMLHTTPRequest present, use that */
        return new XMLHttpRequest();
    } else if (window.ActiveXObject) {
        /*  there are several versions of IE's Active X control, use the most recent one available */
        var xmlVersions = ["MSXML2.XMLHttp.5.0",
                           "MSXML2.XMLHttp.4.0",
                           "MSXML2.XMLHttp.3.0",
                           "MSXML2.XMLHttp",
                           "Microsoft.XMLHTTP"];

        for (var x = 0; x < xmlVersions.length; x++) {
            try {
                var xmlHTTP = new ActiveXObject(xmlVersions[x]);
                return xmlHTTP;     
            } catch (e) {
                //continue looping
            }
        }
    }

    /* if none of that worked, return false, to indicate failure */
    return false;
}