var browserName = navigator.appName;
var browserVersion = parseInt(navigator.appVersion);
var browser;

if (browserName == "Netscape" && browserVersion == 5) {
   browser = "nn6";
}
else if (browserName == "Netscape" && browserVersion == 4) {
   browser = "nn4";
}
else if (browserName == "Microsoft Internet Explorer" &&
        browserVersion == 4 &&
        navigator.appVersion.indexOf("MSIE 6.0") != -1) {
   browser = "ie6";
}
else if (browserName == "Microsoft Internet Explorer" &&
        browserVersion == 4 &&
        navigator.appVersion.indexOf("MSIE 5.5") != -1) {
   browser = "ie55";
}
else if (browserName == "Microsoft Internet Explorer" &&
        browserVersion == 4 &&
        navigator.appVersion.indexOf("MSIE 5.0") != -1) {
   browser = "ie5";
}
else if (browserName == "Microsoft Internet Explorer"
        && browserVersion == 4) {
   browser = "ie4";
}