xmlhttp = null;
	try {
		// Firefox, Opera 8.0+, Safari
		xmlhttp=new XMLHttpRequest();
	} catch (e) {
		// Internet Explorer
		try {
			xmlhttp=new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			try {
				xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {
				alert("Your browser does not support AJAX!");
				exit;
			}
		}
	}

function ajax(url, vars, callbackFunction) {
	if(xmlhttp != null) {
		xmlhttp.open("POST", url , true);
		xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded; charset=UTF-8");
		xmlhttp.onreadystatechange = function() {
			var done = 4, ok = 200;
			if (xmlhttp.readyState == done && xmlhttp.status == ok) {
				if (xmlhttp.responseText) {
						  callbackFunction(xmlhttp.responseText);
					}
			}
		};
		xmlhttp.send(vars);
	}
}