System table or view is deprecated
This SQL Server 2000 system table is included as a view for backward compatibility.
We recommend that you use the current SQL Server system views instead. To find the equivalent system view or views, see Mapping SQL Server 2000 System Tables to SQL Server 2005 System Views. This feature will be removed in a future version of Microsoft SQL Server.
Avoid using this feature in new development work, and plan to modify applications that currently use this feature.
Compatibility Views (Transact-SQL) (MSDN)
Mapping System Tables to System Views (Transact-SQL)
| sysusers | sys.database_principals | Catalog view |