How to prepare your DNN 5 site to run Linq to SQL modules
Now that DNN5 is here you can follow these simple steps to run modules that use Linq to SQL.
1) Install ASP.NET 3.5 (or higher installed on the server)
2) Log in as Host and from the Host menu, navigate to Host Settings.
3) Click on the link that says "Update Site to current Framework".
4) The site will now be upgraded and you can now install and run Linq to SQL modules.
If you have any problems, for example you have partially upgraded the site using the upgrade wizard in Visual Studio, you can install and run this program to upgrade your site: LinqPrep
Use http://www.codeplex.com/DNNLinqToSqlAdapter to create DotNetNuke modules that work with the DotNetNuke object qualifier option setting in the web.config site (see: http://blogs.law.harvard.edu/brandonhaynes/2008/10/14/using-the-linq-to-sql-adapter-in-a-dotnetnuke-module/)
My personal DotNetNuke blog.