utility function for XHR
function get_req () {
		var self = this;
		var req;
		if (window.XMLHttpRequest) {
			try {
				req = new XMLHttpRequest();
			} catch(e1) {
				req = false;
			}
		} else if (window.ActiveXObject) {
			try {
				req = new ActiveXObject("Microsoft.XMLHTTP");
			} catch(e2) {
				req = false;
			}
		}
		return req;
	}