errr.. the explaination says you cant update system tables on sql 2005 onwards. is this description really true?

I'm not saying its a good practice and Microsoft definitely doesnt support the case if you've modified system tables, but ..

http://sqlserver-qa.net/blogs/tools/archive/2007/04/24/sql-server-2005-ad-hoc-updates-to-system-catalogs-are-not-allowed.aspx

Simon