/**
 * create the XMLHttpRequest object
 */
function getObjReq() {
	var request = false;
	try {
		request = new XMLHttpRequest();
	} catch (trymicrosoft) {
		try {
			request = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (othermicrosoft) {
			try {
				request = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (failed) {
				request = false;
			}  
		}
	}

	if (!request)
		alert("Error initializing XMLHttpRequest!");
	return request;
}

function doHttpRequest(url,postData,callbackFunc) {
	var request = getObjReq();
	request.open(postData?"POST":"GET", url, true);
	request.onreadystatechange = function() {
		if (request.readyState == 4) {
			if (request.status == 200) {
				callbackFunc(request.responseText);
			}
		}
	}
	if(postData) {
		request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
		request.setRequestHeader("Content-Length",postData.length);
	}
	request.send(postData);
}