Upgrading SQL Server editions
How to upgrade your SQL Server edition (without reinstalling) With the updated SQL Server 2008 installation program, upgrading SQL Server editions has finally been made as straightforward process as it always should have been.
In SQL Server 2005 upgrading/changing the edition involved running the setup program from the command line with a multitude of specific parameters set.
This blog posting covers SQL Server 2005 and SQL Server 2008.
Before you start, make sure you are on a supported upgrade path as described in the edition upgrade matrix (for SQL Server 2005) on Microsoft’s website.