I think I should be more selective in installing the patches suggested by Susewatcher. Since my Linux box is not directly exposed to the outside world (it sits behind my Windows machine -- I know, it should be the other way around, but since my DSL USB modem works only with Windows, I don't have much choice), the security patches aren't very critical for me.
In addition to incurring bandwidth costs, I suspect that some of these patches could be making the computer intermittently slower; when I perform some action, there is a two/three second delay, followed by a clickety-click from the CPU case and then the machine responds. It's almost as if the computer has gone to sleep and has to be woken up.