function VersionNavigateur(Netscape, Explorer) {
  if ((navigator.appVersion.substring(0,3) >= Netscape && navigator.appName == 'Netscape') ||      
      (navigator.appVersion.substring(0,3) >= Explorer && navigator.appName.substring(0,9) == 'Microsoft'))
    return true;
else return false;
}


<!--
	function openWin( windowURL, windowName, windowFeatures ) { 
		return window.open( windowURL, windowName, windowFeatures ) ; 
	} 
// -->