How do I change the system wide collation setting in SQL Server 2005

I've got a recently upgraded SQL Server which I'm getting ready to put live, we've gone from SQL Server 2000 to SQL Server 2005. The collation setting on the 2005 box is different though (I didn't do the upgrade so not sure if something was done wrong during that process). Is is possible/advisable to change the system wide collation setting in SQL Server 2005, or should I just get the installation done again?

This article (also contains link to MSDN on Microsoft) seems to suggest it can be done and includes instructions, although to be honest it looks like it would be easier just to reinstall!