I uploaded AdventureWorks databases for 2012, 2008R2 and 2008 to http://msftdbprodsamples.codeplex.com/releases/view/93587
. This release consolidates AdventureWorks databases for SQL Server 2012, 2008R2 and 2008 versions to one page. Each zip file contains an mdf database file and ldf log file. This should make it easier for you to find, download, and attach the AdventureWorks databases. There are no database schema changes.