I know that Microsoft made some improvements to the patching process in SQK 2008, but this is so long ago I cannot remember the exact details.

It is always worth taking a backup image of OS and SQL program files and the system databases before applying a patch, so that you can safely revert to the pre-patch situation if a problem arises. Also, it is best to apply patches to non-production machines followed by regression testing before applying that patch to production, as this gives you the opportunity to not apply a patch to a business-critical server.