Yesterday I mentioned that there's no substitute for doing your own testing of updates. I mentioned virtualization is your friend -- building a model of your environment using Virtual PC and Virtual Server will save you a lot of money and it's something you can quickly tear down and rebuild whenever you want. But what if you simply can't test at all, because you simply lack the resources -- time, money, whatever? (You also lack a good manager in this case, but that's a blog entry for another time...)
Check out what Susan Bradley recommends. Stop tweaking, engage with the community. Fewer tweaks increase the likelihood of updates working just fine; the community can be somewhat of an update testing mechanism for you. Technical people love to help, take advantage of the smart ones.
Reading this entry i can tell that a awful lot of people lack a good manager! Why "waste" time and resorces to test patches? (that's what they say all the time)