var browser=navigator.appName;
var version=navigator.appVersion;
var ns4 = false;
var ie4 = false;
if (browser == "Netscape") { var versionnumber=version.substring(0,3); }
else { var msie=version.lastIndexOf("MSIE");
 var versionnumber=version.substring(msie+5,msie+8); }

function getplatform(osversion){
if (navigator.platform >= "Win") {
 return osversion="Win";
 } else {
 return osversion="Mac"; }
}

function itsNetscape() {
 ns4 = true; 
 var osversion = getplatform();
 if (osversion == "Win") {
  document.write('<LINK REL=StyleSheet HREF="ns.css" TYPE="text/css">')
 } 
 else if (osversion =="Mac") {
  document.write('<LINK REL=StyleSheet HREF="nsmac.css" TYPE="text/css">')
 } }      

function itsMsie() {
 var osversion = getplatform();
 if (osversion =="Win") {
  if (versionnumber >= 4.0) {
   ie4 = true  
   document.write('<LINK REL=StyleSheet HREF="ie.css" TYPE="text/css">') }
  else { itsother(); }
 }
 else if (osversion == "Mac") {
  if (versionnumber >= 4.5) {
   ie4 = true  
   document.write('<LINK REL=StyleSheet HREF="iemac.css" TYPE="text/css">'); }
  else { itsother(); }
 }
}

function itsother() {
 window.open("upgrade_browser.html", "_parent");
  }
  
if ((browser == "Netscape") && (versionnumber >= 4)) { itsNetscape(); }
else if ((browser == "Microsoft Internet Explorer")) { itsMsie(); }
else { itsother(); }