Kod:
    procedure TForm1.Button1Click(Sender: TObject);
var
  VolumeSerialNumber : DWORD;
  MaximumComponentLength : DWORD;
  FileSystemFlags : DWORD;
  SerialNumber : string;
begin
  GetVolumeInformation('C:\',
                                     nil,
                                     0,
                                     [MENTION=270981]volume[/MENTION]SerialNumber,
                                     MaximumComponentLength,
                                     FileSystemFlags,
                                     nil,
                                     0);
  SerialNumber := IntToHex(HiWord(VolumeSerialNumber), 4) + '-' +
                           IntToHex(LoWord(VolumeSerialNumber), 4);
  Memo1.Lines.Add(SerialNumber);

end;