I have finally posted up an article I wrote on extending the new VS2005 TableAdapters into a multi-tier architecture. It is quite lengthy and shows one way of leveraging the new TableAdapter/DataSet designer in a 3-tier architecture that supports both WinForms and ASP.NET 2.0... Note that if you are creating only a WinForms client, you may want to instead just use the RowChanged event in the DataSet to do your validation, but that does not lend itself to a web environment. I subsequently did a presentation for our CNY Developer Group this month on the contents of this article.