function checkBrowser() {
	agent = navigator.userAgent.toLowerCase();
	aname = navigator.appName.toLowerCase();
	minor = parseFloat(navigator.appVersion);
	isIE = agent.indexOf("msie");
	isNS = aname == "netscape" ? true : false;
	isMac = agent.indexOf("mac");

	// check for Mac IE 5 or lower
	if (isIE != -1 && isMac != -1) {
		if (minor >= 4) {
			minor = parseFloat(agent.substring(agent.indexOf("msie ") + 5));
			major = parseInt(minor);
			if (major <= 5) {
				// mac ie 4 or 5 detected
				action();
			}
		} else {
			// mac ie lower than 4 detected
			action();
		}
	}
	
	// check for Netscape 4 or lower
	if (isNS) {
		major = parseInt(minor);
		if (major <= 4) {
			// netscape 4 or lower detected
			action();
		}
	}
}

function action() {
	location.href = "unsupported.html";
}

checkBrowser();