public static string AddWorkday(int NumberOfDays, string Format)
{
    DateTime ReturnDate = DateTime.Now;            

    if (NumberOfDays > 0)
    {
        while (NumberOfDays > 0)
        {
            switch (ReturnDate.DayOfWeek)
            {
                case DayOfWeek.Friday:
                    ReturnDate = ReturnDate.AddDays(3);
                    break;
                case DayOfWeek.Saturday:
                    ReturnDate = ReturnDate.AddDays(2);
                    break;
                default:
                    ReturnDate = ReturnDate.AddDays(1);
                    break;
            }
            NumberOfDays--;
        }
    }
    else if (NumberOfDays < 0)
    {
		while (NumberOfDays < 0)
        {
			switch (ReturnDate.DayOfWeek)
			{
				case DayOfWeek.Monday:
					ReturnDate = ReturnDate.AddDays(-3);
					break;
				case DayOfWeek.Sunday:
					ReturnDate = ReturnDate.AddDays(-2);
					break;
				default:
					ReturnDate = ReturnDate.AddDays(-1);
					break;
			}
			NumberOfDays++;
		}
    }
	
    return ReturnDate.ToString(Format);
}