So I managed to do something really stoopid on our computer. Fortunately we own a copy of TechTool Pro, since Disk Utility was unable to repair the hard disk. Unfortunately, TechTool has been running since, oh, about 2am and still isn't finished. It showed fairly swift progress at first, but it's been getting progressively slower since morning. I don't now have any idea when it will finish.
So I'm typing this entry on Susan's old ThinkPad, which she bought used/cheap a year or two ago when she wanted to try on-line poker and all the programs only ran under Windows. It's nice to have something, so I'm not blind and out of touch with the world, but I'm not very comfortable on this machine so I probably won't do as much reading and posting and replying to comments as I would otherwise have.
(And "holding my breath," hoping that the real machine will more or less recover, since the last backup was about a month ago, just before I upgraded from OS 10.3x to 10.4. I'd really rather not loose all that stuff, time, and effort. We'll see.)