SQL Server 2005 Service Pack 2
Extending the Functionality of Your SQL Server 2005 System
Microsoft released Service Pack 2 (SP2) for SQL Server 2005 on Tuesday, a free upgrade available for download, in addition to new virtualization licensing for the database
http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/servicepacks/sp2.mspx
Microsoft said it will allow unlimited virtual instances of the SQL Server SP2 database to run on servers that are fully licensed for SQL Server 2005 Enterprise Edition. More Info on http://www.infoworld.com/article/07/02/20/HNsqlserver2005sp2_1.html