I think we're getting close to the end of this; however, a full Norton AntiVirus system scan -- NAV hadn't been updated for two years; Lisa's father gave me his credit card and said to update to the current version -- is running now. I think I've managed to uninstall or deactivate most of the unwanted programs and system-tray objects such as drivers for printers they don't even own anymore.
But in the meantime, thanks to this entry on bigblued's LJ, I've downloaded the trial version of Ewido Anti-Malware, and I also found nearly 200 bits of malware (mostly tracking cookies) on my machine that my other anti-malware software had missed. I guess I should go ahead and pay the fees.
But the consequence of all this computer work is that I've been "in the office" for nearly four hours how and have gotten nearly no real work done, thanks to fussing about with all these updates, installations, and system scans!