function checkPlugin(plgIn, theURL, altURL, autoGo) {
  var ok=false; document.returnValue = false;
  with (navigator) if (appName.indexOf('Microsoft')==-1 || (plugins && plugins.length)) {
    ok=(plugins && plugins[plgIn]);
  } else if (appVersion.indexOf('3.1')==-1) {
    if (plgIn.indexOf("Flash")!=-1 && window.flash!=null) ok=window.flash;
    else if (plgIn.indexOf("Director")!=-1 && window.dir!=null) ok=window.dir;
    else ok=autoGo; }
  if (!ok) theURL=altURL; if (theURL) window.location=theURL;
}