[ecfisa]

Hola BPL.

Y si deseas mostrar el nombre y número del día,

Código Delphi [-]
uses DateUtils;

function LastDay(const aMonth, aYear: Word): string;
const
  NDAY: array[1..7] of string = ('lunes','martes','miercoles','jueves','viernes','sabado','domingo');
var
  LastDay: Word;
  dt: TDate;
begin
  LastDay:= DaysInMonth(EncodeDate(aYear, aMonth, 1));
  dt:= EncodeDate(aYear, aMonth, LastDay);
  Result:= Format('%s %d',[NDAY[DayOfTheWeek(dt)], LastDay]);
end;

Código Delphi [-]
begin
  ShowMessage(LastDay(2, 2008))
end;

Saludos