You don't get at the tables. They're hidden system tables, you can't even see them let alone query them. Use the catalog views, that's what they are there for.
If you want the table-equivalent of sp_configure, it's sys.configurations.
For the permissions granted to those windows users, you want sys.database_principals (for the users and their roles), sys.database_role_members and sys.database_permissions.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability