Get Computer Net Name and User Windows

function GetComputerNetName: string;
var
  buffer: array[0..255] of char;
  size: dword;
begin
  size := 256;
  if GetComputerName(buffer, size) then
  Result := buffer
  else
  Result := ''
end;

Function GetUserFromWindows: string;
Var
  UserName : string;
  UserNameLen : Dword;
Begin
  UserNameLen := 255;
  SetLength(userName, UserNameLen) ;
  If GetUserName(PChar(UserName), UserNameLen) Then
  Result := Copy(UserName,1,UserNameLen - 1)
  Else
  Result := 'Unknown';
End;

Get Serial Hard Disk

function GetHardDiskSerial(const DriveLetter: Char): string; 
var 
  NotUsed: DWORD; 
  VolumeFlags: DWORD; 
  VolumeInfo: array[0..MAX_PATH] of Char; 
  VolumeSerialNumber: DWORD; 
begin 
  GetVolumeInformation(PChar(DriveLetter + ':\'), 
  nil, SizeOf(VolumeInfo), @VolumeSerialNumber, NotUsed, 
  VolumeFlags, nil, 0); 
  Result := Format('Label = %s VolSer = %8.8X', 
  [VolumeInfo, VolumeSerialNumber]) 
end; 

procedure TForm1.Button1Click(Sender: TObject); 
begin 
  ShowMessage(GetHardDiskSerial('c')); 
end;