Just an FYI that I posted about an issue where a missing db owner can cause discovery to fail over on our new OperationsMgr blog:

http://blogs.technet.com/operationsmgr/archive/2009/01/14/opsmgr-2007-discovery-wizard-never-ends-and-no-computers-are-discovered.aspx

Enjoy!

J.C. Hornbeck | Manageability Knowledge Engineer