Download sample databases (LINQ to DataSet)
The samples and walkthroughs in the LINQ to DataSet documentation use the AdventureWorks sample database. You can download this sample database free of charge. Browse to AdventureWorks sample databases to download the database. Then, follow the instructions on that page for attaching or restoring a database.
SQL Server Express
The samples and walkthroughs in the LINQ to DataSet section use SQL Server 2005 as the data store, but you can modify them to use SQL Server Express instead. SQL Server Express is free, and you can redistribute it with applications.