XmlHttp = {
    _MSXML_PROGIDS:["Msxml2.XMLHTTP.6.0", "MSXML2.XMLHTTP.3.0", "MSXML2.XMLHTTP", "Microsoft.XMLHTTP"],

    create:(function() {
        var request = null;
	    try {
		    // non ie browser
		    request = new XMLHttpRequest();
	    }
	    catch(e) {
		    for (var i = 0; i < this._MSXML_PROGIDS.length; ++i) {
			    try {
				    request = new ActiveXObject(this._MSXML_PROGIDS[i]);
				    break;
			    }
			    catch(e){}
		    }
	    }
	    finally {
	        if(request == null) {
	            alert("Unable to create an XmlHttpRequest, your browser does not support this feature");
	        }
		    return request;
	    }
    })
};

function XmlHttpSendRequest(url, postData, callback) {
    var request = XmlHttp.create();
    request.open('POST', url);
    request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    request.onreadystatechange = function() {
        if (request.readyState == 4) {
            var data = request.responseText;
            callback(data);
        }
    }
    
    request.send(postData);
};