browser_version= parseInt(navigator.appVersion);
browser_type = navigator.appName;

if (browser_type == "Microsoft Internet Explorer" && (browser_version >= 4)) {
	document.getElementById("lnkStyle").href = "/styles/ff.css";
} 
else if (browser_type == "Netscape" && (browser_version >= 4)) {
	document.getElementById("lnkStyle").href = "/styles/ff.css";
}