.net - Calculate A New Date Simply By Using The Build-in Dateadd Function?

I would like to calculate a new date simply by using the build-in dateadd function, but take into account that only weekdays should be counted (or 'business days' so to speak).I have come up with this simple algorithm, which does not bother about holidays and such. I have tested this with some simple dates, but would like some input if this can be done in better ways.This sample assumes a week with 5 business days, monday-friday, where first day of the week is monday. Dateformatting used here is d-m-yyyy, the sample calculates with a startdate of october 1, 2009.

Here is the simple form:

Dim d_StartDate As DateTime = "1-10-2009"
Dim i_NumberOfDays As Integer = 12
Dim i_CalculateNumberOfDays As Integer

[code]....