No matter how far back I went trying to boot from older images, Windowas XP refused to come to life.
So I ordered a new PC, since the dead one was getting pretty old.
I shan't receive it for another 3 weeks because wifie's picking it up from a friend's house in the UK, but I thought it was time to try recovering critical stuff from the old hard drives.
Downloaded ISO CD burner software to this laptop, to overcome XP's inability to create full images on CD. Downloaded Ubuntu and burned a CD.
Fired up old PC, and got the usual black screen with suggestions about booting with checks turned off, but boot continued untouched - AND MY PC CAME BACK TO LIFE.
All the same, I'm copying critical stuff to an external drivebefore I try teh idea of booting Ubuntu from CD. That experience is sure to come in handy another day.