var ieVersion = parseFloat(navigator.userAgent.substr(navigator.userAgent.indexOf("MSIE") + 5, 3));
var nsVersion = parseFloat(navigator.userAgent.substr(navigator.userAgent.indexOf("Mozilla") + 8, 3));

var isIE = (navigator.appName == "Microsoft Internet Explorer" && ieVersion >= 4 && !window.opera) ? true : 
	false;
var isIE55 = (navigator.appName == "Microsoft Internet Explorer" && ieVersion >= 5.5 && !window.opera) ? 
	true : false;
var isNS4 = (navigator.appName == "Netscape" &&	nsVersion < 5 && nsVersion >= 4 && !window.opera) ? true : 
	false;
var isNS5 = (navigator.appName == "Netscape" &&	nsVersion >= 5 && !window.opera) ? true : false;