Detectando o número serial do HD

function SerialNum(FDrive: String): String;
var
serial: DWord;
DirLen, flags: DWord;
DLabel: array[0..11] of Char;
begin
try
GetVolumeInformation(PChar(FDrive+':\'), DLabel, 12, @serial, DirLen, flags, nil, 0);
result:= IntToHex(serial, 8);
except
result:= '';
end;
end;