Only thing else I can do is install XP. Anyone still running that? Is it safe?
If it's gotta be windows, I'd go with win-7 over xp if for no other reason than it supports more recent software. But, yes, if you run a (good) firewall, AV and don't do dumb things online like opening attachments from emails you don't know or are obvious scams, use Virtual-Box and do a dump after your online session and use a VPN, then it's just as safe as you make it. It all depends on your online activity, personal savvy and level of paranoia.
'Safe' is a relative term.
OSX and linux can be hacked just like windows, but win has the biggest user base so it's the most productive target with the most 'holes' exposed.
If you need an OS, it seems you can get either xp or 7 for under 50 bucks, sometimes as little as 19 bucks (though from your post, I assume you already have a copy of xp).https://www.amazon.com/s/ref=nb_sb_noss_1/191-5532507-9060804?url=search-alias%3Daps&field-keywords=windows+xphttp://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR12.TRC2.A0.H0.Xwindows+xp.TRS0&_nkw=windows+xp&_sacat=0
Be aware that if you buy a 'branded' OEM version (say, for a Dell) and the machine you're installing to is something else (like an ACER), the SLIC table in the ACER BIOS won't match the license key on the Dell OEM disk and you may have to mod the bios to get it to install (so to be safe, don't buy a branded OEM distribution).
However, for future reference, should you ever need to do this, this is probably the best place to go for help/tools/mods:https://www.bios-mods.com/
I had to do this to deal with a BIOS 'whitelist' issue for a video card upgrade a few years ago and they were very helpful.