With SQL 2005, a new version of Workgroup Edition to the SQL Server family will be added. The picture shows the different editions offered by SQL Server 2005 with the addition of the new Workgroup Edition.
SQL Server 2000 Workgroup Edition supports up to 2 CPUs, 2 gigabytes of memory, and an unlimited database size. Workgroup Edition is a great entry-level database for smaller departments in a larger organization or for businesses that have outgrown MSDE or even Small Business Server Premium Edition, which includes SQL Server 2000. However, if you are looking for business intelligence capabilities, you will want to evaluate SQL Server Standard Edition because it provides the complete SQL Server set of components including our award-winning Analysis Services, Reporting Services, and data-mining technologies.
See: http://www.microsoft.com/sql/spotlight/expandsqlserver.asp