As explained in this Microsoft KB article, there are two versions of the SP2 download for SQL Server 2005. Here is the "good" version of the SQL Server 2005 SP2 download. Notice the 9.0.3042.1 file version. The newer version was released on March 5.
Here is the original, "bad" version. Notice the 9.0.3042.0 file version.
Technorati Tag: SQL Server
