/*
get browser type
*/
var isNav, isIE;
if (document.all) isIE = true;
if (document.getElementById) isNav = true;

/**
 * Takes querystring URL as argument
 * AJAX call function
 * @return string
 */
function do_ajax_call(url) {
	
	if (isIE) {
		var xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
		xmlhttp.Open("POST", url, false);
		xmlhttp.SetRequestHeader("Content-Type", "application/x-www-form-urlencoded");
		xmlhttp.Send("");
		responseString = xmlhttp.responseText;
	} else {
		if (isNav) {
			var xmlhttpNav = new XMLHttpRequest();
			xmlhttpNav.open("POST", url, false);
			xmlhttpNav.send(null);
			responseString = xmlhttpNav.responseText;
		}
	}
	//alert(responseString);
	return responseString;
}