Changing to Windows Authentication Only mode won't affect the databases. For instance, when you set up a SQL Server out of the box with Windows Authentication, master, model, msdb, Northwind, pubs, and tempdb are all owned by sa. The db_owner is internal to SQL Server.... it's a mapping between sysxlogins and sysdatabases. So long as the SID exists in sysxlogins, you should be okay Since sa can't go away... you get the idea.

As far as jobs are concerned, they will continue to run with an owner of sa (I just checked a SQL Server that's Windows only and we do have a job running under sa). Typically, though, we run with the owner as the service account for SQL Server/SQL Server Agent (which needs sysadmin rights to SQL Server anyway).

What changing will do is prevent anyone from logging in as sa (once you restart the service after makingt he change). The sa account will still be present and if you ever switch it back, the sa account will be available again for login. By switching to Windows only authentication, you stop all SQL Server logins, but you don't get rid of them or make them invalid.

K. Brian Kelley

http://www.truthsolutions.com/

Author: Start to Finish Guide to SQL Server Performance Monitoring

http://www.netimpress.com/shop/product.asp?ProductID=NI-SQL1