virtualbox.org

Wow, I'm overwhelmed that you'd go to the trouble of making such an elaborate set of instructions for me!

I was not able to do the compare in your step 3, couldn't determine the correct parameters to make the compare.
I did copy the WinXP virtual machine and VDI files (copied both to 2 separate backup locations, so I kept 2 sets)... but couldn't do the compare to the original.
Seemed unlikely that they were could be copies, size is identical, so I pushed on.

But at the end, when I booted WinXP Rescue, it failed with a "FATAL: Could not read from the boot medium! System halted."
I then mucked around in settings and discovered there was no hard drive in the storage settings, so I corrected that, AND IT BOOTED!
Removed the original bad virtual WinXP.

So now I have a WinXP that boots, and backups of it.
I haven't yet tried adding a second monitor.

Many Thanks!!!!

No problem, glad to help!

Go ahead and slide that monitor switch and see what happens.

regarding FC file compare, btw, it's an easy process:
Open a command prompt.
type FC then a space.
drag-n-drop the source file into the command window, then click in the command window. The full path and name of the source file will appear in the command window.
Type another space in the command window.
Drag-n-drop the copy of the file into the command window then click in the command window. Now the path and name of the copy appears.
hit Enter.
If the files are identical, a message "no differences encountered" will appear. This means the file copied properly and can be trusted as a good backup.

(BTW, don't bother testing the copies now. The successful boot will have changed at least some log files in the guest OS so the FC will fail even if the copies are good.)

My thanks again.

One niggling issue remains: although I've installed Guest additions, and the USB ports in the WinXP guest all look fine (drivers loaded, "this device is working properly"),
when I insert a flash drive in a USB port, it always comes up in the Win10 host, never in the virtual WinXP.
When I had this setup running under Win7, I merely had to click my mouse on the WinXP guest desktop, then insert the flash drive; that doesn't work now.

OK< I don't know much about how to get that going, I don't use USB in my guests almost at all, last time some couple years ago. I would recommend a new topic.
First try a google or bing search "USB in Guest site:forums.virtualbox.org"

Thanks, I will.
Added second display and it worked fine.

Nice! Glad it's working.
Just one of those glitches, then...