function getAppVer() { return( parseInt(navigator.appVersion.charAt(0)) ); }
function isNav() { return( navigator.appName == "Netscape" ); }
function isIE() { return( (navigator.appName.indexOf("Microsoft") != -1) ? true : false ); }
function isNav4() { return( isNav() && (getAppVer()<=4) ); }
function isNav6() { return( isNav() && (getAppVer()>=5) ); }
function isFireFox() { return ( (navigator.userAgent != null) && (navigator.userAgent.indexOf( "Firefox/" ) != -1) ); }