Dim gc As New GregorianCalendar()
        Dim cwr As CalendarWeekRule = _
          System.Threading.Thread.CurrentThread.CurrentCulture.DateTimeFormat.C_
          alendarWeekRule
        Dim dow As DayOfWeek = _
        System.Threading.Thread.CurrentThread.CurrentCulture.DateTimeFormat.Fir_
        stDayOfWeek
 
        TextBox1.Text = gc.GetWeekOfYear(DateTime.Now, cwr, dow)