function open_url(u, data_event) {
	var ajaxRequest = null;
	try {
		// Mozilla
		ajaxRequest = new XMLHttpRequest();
	} catch (e) {
		// IE
		try {
			ajaxRequest = new ActveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
		}
	}
	
	ajaxRequest.onreadystatechange = data_event;
	
	ajaxRequest.open("GET", u, true);
	ajaxRequest.send(null);
	
	return ajaxRequest;
}