I believe it's possible to set the updates to install when you shutdown. (at least in Windows) as for Adobe, they aren't the only PDF reader on the market... (
http://www.foxitsoftware.com/pdf/reader/ for example) And the Adobe Reader package has turned into quite the bloatware for such a simple function...
And like jekostas said, the Macs don't get updates pushed out due to the fact that the exploits are rarely exploited as they have a very small market share... much more sense that spam and botnets and all that to exploit several million windows machines... I suspect the Mac elitist attitude that nothing bad will ever happen to their Macs will eventually bite them in the ass... ignorance is not the best security measure.
I think I'd rather be annoyed by regular updates than my systems exploited.
What I do hate is on my PC connected to the TV, which runs Boxee (on win7) now, and before that Mediaportal (on XP home), that since the machine is set to run the media playing software on startup I don't see the updates pending messages and all that... so sometimes we're watching a program or movie and suddenly windows decides to reboot. Mind you since the upgrade to Win7, that hasn't happened (I set the updates to apply on shutdown) Quite tempted to wipe the box again, and setup Ubuntu 10.10