Como obter o número do dia da semana no .net

function DiaDaSemana(const Data: DateTime): Word;
var
  DiaAtual: DayOfWeek;
  brCulture : System.Globalization.CultureInfo;
  ptCal     : System.Globalization.Calendar;
begin
  brCulture := System.Globalization.CultureInfo.Create(´pt-BR´);
  ptCal     := brCulture.Calendar;
  DiaAtual := ptCal.GetDayOfWeek(DateTime.Today);
  case DiaAtual of
    DayOfWeek.Sunday:    Result := 0;
    DayOfWeek.Monday:    Result := 1;
    DayOfWeek.Tuesday:   Result := 2;
    DayOfWeek.Wednesday: Result := 3;
    DayOfWeek.Thursday:  Result := 4;
    DayOfWeek.Friday:    Result := 5;
    DayOfWeek.Saturday:  Result := 6;
  end;
end;