Prandy -- In January of 2005, I had to reformat my hard drive after my Registry was corrupted by upper-level Microsoft technicians trying to fix a situation with my system information file that could not be fixed. The overall opinion of all of these upper-level techs was that the source of my problem was a result of one of the Windows Updates either not downloading properly or being corrupted.......even WU is not perfect all the time.
My point is that the art of the computer is not perfect, nor is Windows Update or Microsoft. There are times when we know our own computer and need to make a judgment call. It is my feeling that I want to exercise as much control over what comes into my computer as possible, without jeopardizing safety and security. One of the methods I find works best for me is to investigate each recommended Critical Update, using the referral links given on WU, before allowing into my computer.
I do not like to use ''automatic'' anything on my computer, including downloading virus defs and other security settings. It is a habit I picked up using Windows 98....all the ''automatic'' settings needed to be running all the time which reduced the system's resources. In all probability, XP does a better job of handling.
Having said all that, the ''automatic'' settings are critical for those who forget to check daily for new virus def and security updates, WU on a regular basis, maintenance, or any programs needed to keep the computer healthy.......and CNET forums, of course 
Just my two cents' worth.....
Miki