Microsoft have released a new sample database for SQL Server 2005 which is much simpler than AdventureWorks. It's still based on the same scenario, and it still (frustratingly) uses singular table-names (like Person, not People), but this is certainly going to be useful for all kinds of demonstrations. It really helps to have a model that is easy to understand, and this database, with far fewer tables, is much easier to get your head around. I will probably start using this in the user-group, and any other times when I want to demonstrate a piece of functionality.
Download it from here