The Community Technology Preview (CTP) version of Microsoft SQL Server 2005 Service Pack 1 is now available. You can use these packages to upgrade any of the following SQL Server 2005 editions:
Note: To upgrade SQL Server 2005 Express Edition, obtain the SP1 CTP version of Express Edition. These packages have been made available for general testing purposes only. Do not deploy the CTP software in production. Peer-to-peer support is available in the SQL Server 2005 forums.
Download: SQL Server 2005 CTP March 2006