One of the first and hardest things to achieve when a new version comes out it get rid of old habits. I'm sure you all used the sysobjects, syscolumns, ... and many others quite often. With SQL Server 2005 however there are some changes and lots of these tables have replacement views and extra information although the old tables are kept for backward compatibility.
Check the BOL for "Mapping SQL Server 2000 System Tables to SQL Server 2005 System Views"
This contains a nice overview of the old tables and their new replacement view. Also remember the ANSI standard INFORMATION_SCHEMA views which still exist in SQL Server 2005 of course.