Denny Cherry reminds us that SQL Server 2005 is no longer PCI compliant:
If you are running a PCI compliant system on SQL Server 2005 you are going to fail your next audit. One of the audit requirements is that the vendors must support the version of your software which you are running on. As Microsoft no longer offers support for SQL Server 2005 that’s going to cause you to fail your next PCI audit.
Microsoft’s serious about sunsetting old versions of SQL Server, and at this point, there have been five versions of SQL Server released since 2005.