Since @ryanprior and @yomimono were the only ones who answered, I've tried installing @elementary on Dad's old laptop. The installer left a system that showed logo, briefly flashed a login on tty1, and then black screened, but I could go back to tty1 and fix things so I can do a graphical login now. Not a great first impression, but I'll let it have its updates, install the stuff my sister wants to use, and see how things go.