Public Function WeekDays(ByVal nYear As Integer, ByVal nWeek As Integer) As _
  ArrayList
        Try
            Dim arrWeekDays As New ArrayList
            Dim nTempWeek As Integer
            Dim tmpDate As New Date(nYear, 1, 1)
            nTempWeek = 1
            While nTempWeek <= nWeek
                If tmpDate.DayOfWeek = DayOfWeek.Monday Then
                    nTempWeek += 1
                End If
                If nTempWeek = nWeek Then
                    arrWeekDays.Add(tmpDate)
                End If
                tmpDate = tmpDate.AddDays(1)
                If tmpDate.Year > nYear Then Exit While
            End While
            Return arrWeekDays
        Catch ex As Exception
            Return Nothing
        End Try
    End Function

Dim myWeeks As ArrayList
        myWeeks = WeekDays("2004", 53) 'alle tage der 53 woche im jahr 2004
        For i As Integer = 0 To myWeeks.Count - 1
            MsgBox(CType(myWeeks(i), Date).DayOfWeek.ToString)
        Next