var browser = "";
var browsername = navigator.appName;
var browserversion = parseInt(navigator.appVersion);
if (browsername == "Netscape") {
    browser = "ns" + browserversion;
} else {
    if (browsername == "Microsoft Internet Explorer") {
        if (browserversion >= 4) {
            browser = "ie" + browserversion;
        } else {
            browser = "ie3";
        }
    }
}

function popNav(url,name,features) {
   if ((browser == "ns3","ns4") || (browser == "ie4")) {
   popBox = window.open(url,name,features);
   popBox.focus();
     } else {
          if (browser == "ie3") {
          popBox = window.open(url,name,features);
          }  
   }
}