Thanks for the advice. I'll do a bit of research on a Repair Install, and take a look at the SevenForums link you provided. Before proceeding, I'll make sure I have a current full backup.
I am a bit surprised that I need to reinstall Windows, as everything else (except Windows Update) 'seems' to be working fine, and as I mentioned above, Windows Update was also working fine up until last month. At some point last month I changed from updates "For Windows only" to updates "For Windows and other products from Microsoft Update" (basically I enabled Microsoft Update when I was updating Silverlight). Could changing this setting have screwed up Windows Update on my computer? Thanks.