var browser, version, br,
 browser = navigator.appName;
 version = navigator.appVersion
 br = "";
 if ((browser.indexOf("Explorer") >= 0) && (version.indexOf('4.0') >= 0))
 {
   //alert("MSIE 4.0 is present");
   links = document.all.tags("link");
   links[0].disabled=true;
   links[1].disabled=false;
 br = "ie4";
 }
 else if ((browser.indexOf("Netscape") >= 0) && (version.indexOf('4.0') >= 0))
 {
   //alert("You are using Netscape ver.4.x,. \n\n" );
   br = "nn4";
 }