My cheap PS/2 keyboard and mouse showed up today. Good news! They work. I was able to navigate to the device manager and observe a few error codes. They fall under Network Adapters, Sound/video and game controllers, and USB controllers, as expected. It would appear as if the drivers for all of these devices are no longer working. Now the bad news: I reinstalled the drivers, the motherboard chipset.... and it didn't work. The installs completed, and the error message persists. I tried restarting, no effect. I am going to look into a system restore next.
Well, crap: apparently I don't have any system restore points other than today. What else can I do?