I'm an NT admin for a large New Engalnd University (pity me) and I install the updates as soon as they are released. I check to see what they are for first, and make sure they wont conflict or break any server software that might be running, and if they're ok then I go ahead and patch em.
We had nimda pretty bad and my servers remained unscathed.
The rest of the network was hosed so it didnt really matter that they were up, but I was happy.