function createRequestObject() {
    var $vObj;
	if (window.XMLHttpRequest) { // Mozilla, Safari,...
		$vObj = new XMLHttpRequest();
		if ($vObj.overrideMimeType) {
			$vObj.overrideMimeType('text/xml');
		} // fi
	} else if (window.ActiveXObject) { // IE
		try {
			$vObj = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			try {
				$vObj = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {}
		} // fi

		if (!$vObj) { // failed, cannot create
            return false;
        } // fi
	} // fi
    return $vObj;
}

var $vAJAX = createRequestObject();
var $globAJAXBusy = false;

function checkAJAX() {
	if ($globAJAXBusy) {
		$vAJAX.onreadystatechange = function () {}
		$vAJAX.abort();
	} // fi
}

function requestPage($pURL) {
	checkAJAX();
    $vAJAX.open('GET',$pURL,true);
	$globAJAXBusy = true;
    $vAJAX.onreadystatechange = handleResponse;
    $vAJAX.send(null);
}

function postPage($pURL,$pParams) {
	checkAJAX();
	$vAJAX.open('POST',$pURL,true);
	$globAJAXBusy = true;
	$vAJAX.setRequestHeader("Content-type","application/x-www-form-urlencoded");
	$vAJAX.setRequestHeader("Content-length",$pParams.length);
	$vAJAX.setRequestHeader("Connection","close");
	$vAJAX.send($pParams);
	$vAJAX.onreadystatechange = handleResponse;
}

function handleResponse() {
    if(typeof($vAJAX)=='undefined' || $vAJAX.readyState!=4){
		return false;
	} // fi
	
	try {
		if ($vAJAX.status!=200) { // error page
			return false;
		} // fi
	} catch(e) {
		return false;
	} 

	$globAJAXBusy = false;
	var $vResult = $vAJAX.responseXML;
        ..... // do something
}