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 8.0") != -1) {
    browser = "ie8";
}
else if (browserName == "Microsoft Internet Explorer" && browserVersion == 4 && navigator.appVersion.indexOf("MSIE 7.0") != -1) {
    browser = "ie7";
}
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";
}

if (browser == "nn4" || browser == "ie4") {
    document.write('<h4>Achtung! Diese Seite benötigt mindesten den Internet Explorer ab Version 6 (oder einen kompatiblen Browser) !</h4>');
}

if (browser == "ie55" || browser == "ie5") {
 	document.write('<h4>Achtung! Diese Seite benötigt mindesten den Internet Explorer ab Version 6 (oder einen kompatiblen Browser) !</h4>');
}

// Quelle Script: http://www.zudila.ch/scripte/js_browser.php
// Zudila alte Browser erkennen 1.0, GPL