procedure TForm1.Button1Click(Sender: TObject);
var
  FileChangeHandle : THandle;
  subFolders: longbool;
begin
  //subFolders := true;
  //the above works in D2 only ...
  //(otherwise integer(subFolders) == -1)

  //subFolders := longbool(1);
  //the above works in D2 & D3 only ...
  //(otherwise integer(subFolders) == -1)

  //Delphi 2 to 7 ...
  cardinal(subFolders) := 1;

  FileChangeHandle :=
      FindFirstChangeNotification('c:\', subFolders, 
          FILE_NOTIFY_CHANGE_FILE_NAME);
  if (FileChangeHandle = INVALID_HANDLE_VALUE) then
    self.caption := 'Bummer :-('
  else
  begin
    FindCloseChangeNotification(FileChangeHandle);
    self.caption := 'It worked!';
  end;
end;