Thanks to all who sent me X00s - I've finally got it running again!
Partway through, though, I left my pooter switched off but still
connected via its serial port to my sprinkler controller (which I
often do), and a thunderstorm came through, and a nearby lightning
strike knocked out our power for a while (according to our
neighbour, we were all out).  The cables to the sprinkler solenoids
must have acted as antennae, or maybe our 240V earth was
sufficiently different from the sprinkler controller earth, because
when I got home both of the serial ports on my pooter were dead, and
the RS232 signal from Drip (the sprinkler controller) was iffy.  I
replaced the MC1488/1489 RS232 chips in Drip, but the com ports on
the pooter were still dead.  A couple of days later, Win98 failed,
and would only start in Safe mode.  WinXP would only get as far as
its 1st advertisement page.  I took the pooter to a surgery, and it
got a motherboard transplant.  Now its video system is different,
and the monitor doesn't want to know about Win98 screen resolutions
greater than 800x600 - it comes up with a little message that says
"Attention:  67K/74Hz is out of range" (or 68K/84Hz, 64K/59Hz, etc)
XP runs ok at 1024x768, but no higher.  So now I'll need a new
monitor as well.  Drat.

Cheers, and thanks again.

...I'm not a complete idiot. Some pieces are still missing.

--- PPoint 1.88