function makeRequest(url, callback) {
	var httpRequest = false;
	if (window.XMLHttpRequest) { // Mozilla, Safari,...
		httpRequest = new XMLHttpRequest();
		if (httpRequest.overrideMimeType) {
			httpRequest.overrideMimeType('text/xml');
		}
	}
	else if (window.ActiveXObject) { // IE
		try {
			httpRequest = new ActiveXObject("Msxml2.XMLHTTP");
		}
		catch (e) {
			try {
				httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
			}
			catch (e) { httpRequest = false; }
		}
	}
	if (!httpRequest) {
		return false;
	}
	if (callback != null)
		httpRequest.onreadystatechange = function() { eval(callback + '(httpRequest)'); };
	httpRequest.open('GET', url, true);
	httpRequest.send(null);
}