Regarding Linux, one of the great things about it is that you don't have to INSTALL it. You can run it off a CD-ROM or a flash drive. Then when you're done saving files, move them off to another flash drive, shut down, remove the Linux boot medium, and reboot the machine. Wa-la, you're back in Windows (sympathies).
I recommend the 7.x versions of Knoppix. 7.6 works well on most machines. I have one laptop that will only boot off 7.7 (not recommended if you have any other option). I haven't tried the new 8.x series. See
http://www.knoppix.net/ for downloads.
Another good option is to use a Raspberry Pi. Firefox will (barely) run on a Pi 2, Pi 3, or Pi 4. I haven't tried it on a Pi Zero but would expect it to be almost unusably slow. The Zero is $5, the Zero W is $10, the 2-3-4 were base priced at $35 last time I looked (the 4 optionally has more memory for higher prices).
BTW, I'm not suggesting banning katfiles, but it's one of the worst I've used. They repeatedly try to redirect your browser to other sites; blocking those sites in the /etc/hosts file (or whatever Windows uses) will at least prevent the popups from successfully loading. Katfiles also now refuses to work if you have AdBlock installed at all, even if you disable it. I don't know how or why it detects it or why it cares so much (other than wanting people to leave their machines open for viruses).
