在Delphi7中,如何检索硬盘唯一的序列号？

function GetDiskSerialNumber: string;
var
  hDrive: THandle;
  dwSerialNumber: DWORD;
  lpVolumeNameBuffer: array[0..MAX_PATH] of Char;
  nVolumeNameSize: DWORD;
begin
  Result := '';
  hDrive := CreateFile(PChar('\\.\C:'), GENERIC_READ or GENERIC_WRITE,
    FILE_SHARE_READ or FILE_SHARE_WRITE, nil, OPEN_EXISTING, 0, 0);
  if hDrive <> INVALID_HANDLE_VALUE then
  begin
    try
      if DeviceIoControl(hDrive, IOCTL_STORAGE_GET_DEVICE_NUMBER, nil, 0,
        @dwSerialNumber, SizeOf(dwSerialNumber), nil, nil) then
      begin
        Result := IntToHex(dwSerialNumber, 8);
      end;
    finally
      CloseHandle(hDrive);
    end;
  end;
end;