This would probably be a good editorial, but I thought I'd drop it out here as a short note.
You ought to be tracking the build (or version) of all your SQL Server instances and Windows. I'd suggest you automate this, maybe even drop it in a table in every (user) database every day.
With the constant release of patches, the changes you might make to a server, it's easy to lose track of what build a server is at. You might think all your servers are at SP1 or SP2, but you never know when an application might not support the latest version and you're behind.
The more time that passes between the application or deployment of patches, and a disaster, the less likely you'll be sure of what patch level you're on. And if you have dozens of instances, you won't be sure.