[Juanito-Kun]

function ComputerName: string;
var
  Buffer: array[ 0..MAX_COMPUTERNAME_LENGTH ] of Char;
  MaxSize: DWORD;
begin
  MaxSize := SizeOf( Buffer );
  if not GetComputerName(Pchar(@Buffer),MaxSize) then
    raise Exception.Create( 'No puedo determinar el nombre de la máquina' );
  Result := StrPas( @Buffer );
end;