function GetDiskSerialNumber(Drv: String): String;
var
  N, F: DWORD;
  S: PDWORD;
begin
  GetMem(S, 255);
  try
    GetVolumeInformation(PChar(Drv), nil, MAX_PATH + 1, S,
      N, F, nil, 0);
    Result:= IntToHex(HiWord(S^), 0) + '-' + IntToHex(LoWord(S^), 0);
  finally
    FreeMem(S, 255);
  end;
end;