c# DateTime to Add/Subtract Working Days

Based on Taz’s link:

public static class DateTimeExtensions
{
  public static DateTime AddWorkDays(this DateTime date, int workingDays)
  {
    int direction = workingDays < 0 ? -1 : 1;
    DateTime newDate = date;
    while (workingDays != 0)
    {
      newDate = newDate.AddDays(direction);
      if (newDate.DayOfWeek != DayOfWeek.Saturday && 
          newDate.DayOfWeek != DayOfWeek.Sunday && 
          !newDate.IsHoliday())
      {
        workingDays -= direction;
      }
    }
    return newDate;
  }

  public static bool IsHoliday(this DateTime date)
  {
    // You'd load/cache from a DB or file somewhere rather than hardcode
    DateTime[] holidays = 
    new DateTime[] { 
      new DateTime(2010,12,27),
      new DateTime(2010,12,28),
      new DateTime(2011,01,03),
      new DateTime(2011,01,12),
      new DateTime(2011,01,13)
    };

    return holidays.Contains(date.Date);
  }
}