Definitely worth upgrading rather than replacing. 

If it's extremely slow, then as well as the SSD upgrade mentioned, a fresh install of Windows is a good idea, it's quite possible some malware (virus, cryptominer, or similar) has got on there and is causing the PC to run slowly.

gzt: Are any bios changes required?

If its doing legacy booting, then no change needed. If UEFI boot then you may have to go in once and choose the boot order again if it doesn't see the drive as the default after the clone.

ok, so back to me for a moment.

I have a Veeam backup of the AiO.

Can I use the Veeam restore feature for the SSD rather than cloning from the HDD directly?

Just throwing this out there - thought it may be too late.

I have two machines of similar spec I purchased second hand at the start of the first lockdown for the kids to do remote learning on. I upgraded both to SSD's.

These processors are terrible. Just terrible. They were bad when released, and now just horrible. In my experience even running demanding websites on them can be just too much.

I would highly recommend replacing them if possible.

I've already got rid of one, and looking to get rid of the other when I can get another decent second hand machine.

@cokemonz , I suspect you are right, however I have to give it a try.

A shared library Windows machine. How infested with spyware and viruses is it? 

@gzt , perhaps. I'll do the SSD first and see where that gets us.

Do library consoles already run on some sort of VDI? You could virtualise and turn the unit into a thin client.

@yitz , it's not a library computer. It's our pc, located in the library.

So far so good, only took an hour to get the back cover off, and I think I've broken both my thumbs. 😬

I hope it works without the cover on, coz I might to have switch the disks in and out before I'm all done.

So here is an extra question.

We have a collection of CD's (stop sniggering) that contain databases and little programs that access the data.

I have copied most of these to ISO, and for the few that I use at home, I launch the ISO as a Drive Letter and I can then run the program which insists the CD be loaded.

There will be room on the SSD to store these ISO files.

Is there a way of auto-launching the ISO when you run the program?