Sometimes you need the actual day name of the date and not the numeric equivalent, the following function will do that for you:
Public Function MyWeekDayName(dteDate As Date) As String

'Will return "Monday", "Tuesday", etc. based on the date supplied
MyWeekDayName = WeekdayName(WeekDay(dteDate), False)

End Function
Example use in debugger window:

?MyWeekDayName(#10/19/2009#)

Monday