Updating this thread since I found a solution. Someone out there may find this information useful.
First off, in my ignorance, I assumed this Canon BJ-200 needed a 25-pin female connector. It doesn't. It needs a 36-pin Centronics! The printer cable we've had attached to this printer since . . . 1993? It's an adapter cable to connect a 36-pin female Centronics connector to a 25-pin female LPT port on an old PC. All I had to do was pull the adapter cable and, bam, I found the Centronics port on the printer. Duh.
grumble grumble
Anyway, against my advice, my mother went with a USB to Centronics cable (I recommended some of the mini print servers linked above). She bought it locally at Office Depot so she could return it if it didn't work. What she wound up with is an Ativa 828-565 for about three times as much as she could have bought it from eBay. Oh well.
Anyway, the OS gave no indication that it detected anything new installed once this thing was plugged in (I made sure to plug it in while the computer was off). However, when installing a legacy (non-PnP) printer device from device manager, one of the port options was "USB001: Virtual printer port for USB". So I selected that.
Then it asked me to select a driver, but there wasn't anything from the BJ series listed, so I asked Windows Update to extend my list of available print drivers. After about 10 minutes of downloading (slow connection), I found "Canon Bubble-Jet BJ-F200" on the list. I selected that driver, and it worked.
So, yes, you can run a Canon BJ-200 printer under Windows 8 using an Ativa 828-565 USB-to-Centronics cable.
Despite charging a lot of money for this cable, I have to give props to Office Depot for deciding to carry a product that not only works, but works with the latest version of Windows AND with a PC she bought in their store (again, against my advice, but she didn't want a refurb from Tiger Direct, oh well). So maybe they earned their extra bucks by not carrying a confusing array of crap that might or might not work.