UPDATE: Yup, the AirPort Extreme Base Station worked like a charm. Back to normal now.
Evidence indicates that it is indeed our wireless router at fault for the slug-like behaviour of the Wi-Fi networking in our house. I think this will be a good excuse to purge the ungainly stack of networking gear...
...and replace it with a single wireless router that can do everything with fewer wires and, with luck, less general flakiness. Some of that stuff is only 10BaseT or 10Base2 speed, and has been blinking away in our den closet for a decade.
Labels: apple, geekery, techsupport, web