Where can I download the SQL Server 2008 R2 CTP?
MSDN and Technet subscribers can download 2008 R2 Enterprise Edition now for free. Check in the SQL Server 2008 section of the download site, or click here to download SQL Server 2008 R2 for free. Keep in mind that this is a preview build, not a feature-compete beta. It should not be used in production. When databases are attached to a SQL 2008 R2 server, their version number is upgraded to 660, and these databases cannot be reattached to an older (SQL 2008) server.