Date Validation (2)

We have a online shop in the Netherlands and we deliver after 3 full business-days. We are looking for a script who is counting business-days for our customers, so if someone order on monday 13 september, the script will tell them that they can expect their order on friday 17 september. It also must be possible for the customer to pick-up another date (by a calendar in European style) but only after 3 business-days. What we want is a script which we can implement in our orderform.