I use a combination of VNC over an SSH tunnel to access my wife's computer from work. This allowed me to troubleshoot her computer when the need arose ("I've lost an important file...", "I can't print...", etc.), making both my wife and me happy.
So I tried, using the same trick, running windows update on my wife's machine. During the installation process ZoneAlarm popped up one of its oddly shaped dialog boxes, letting me know that a certain program is attempting to connect to the Internet, and asked whether I want to allow that to happen. Since that program was obviously launched by the windows update installer, I assumed it's as harmless as any Microsoft application can possibly be, pointed my mouse towards the appropriate button and attempted to "press" on it by clicking the left mouse button.
To my surprise, nothing happened. The mouse and keyboard seemed to have no effect on any ZoneAlarm dialog box, including the pop-up context menu that appears when right-clicking the ZoneAlarm tray icon (I wanted to shut it down...).
It took a quick search to figure out that I had to disable the "Protect the ZoneAlarm client" option in the ZoneAlarm preferences tab, in order for it to play nicely with VNC. But this is impossible to do from within VNC...
I killed the window update process, waited patiently for my wife to return home and then guided her to click for me in the right place, while I was watching her moves through VNC.
Later on I tried running windows update again, and this time it worked without a hitch. So boring. Just the way I like it.