Best practice is to add a "Class Library" project to your solution and put there your all the content of your BLL folder. Mappings in a class library project CAN be set as embedded resources. Then you can use a web.config file as described in the documentation
http://www.hibernate.org/hib_docs/nhibernate/html/quickstart.html#quickstart-intro (just make sure that the <configSections> is the first item after <configuration>). This works fine in VS 2005.
Hector Cruz
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