Detectando o Numero 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;