I'm a big fan of XP, still. I've got XP machines still running. Also Win2k. They're mostly isolated, as it happens, and I probably wouldn't use them in a perma-online sense (precautionarily), and I currently only connect them with USB keys/drives moving data to and from them in a sufficiently safe (if slow) method, as and when I've got use the sneakernet method to shuffle things about.
But I'm finding that several things are stopping working on XP. DF is Ok (except if it hits the 32-bit memory limit), but the latest versions of Therapist won't work at all (maybe if recompiled, on a more legscy compiler, but currently seems to want something that doesn't get used in the post-XP world of APIs and/or DLLs, but not present at all within XP) and even LCS fails on me (similar reasons, I suspect).
Windows 7 is the one I'd go for, if I was in your position. Vista is just... Nope. Win8 likewise, but then I'm maybe snobbishly against the UI revamp. And Win10's additional bells and whistles probably would cause problems on ex-XP hardware. (Jumping to 7 is a small risk, and keeping it on 7 has been a problem, with the auto-update-to-10, thing, which I think has expired now.) I still haven't done too much with my own 10 machines, to be honest, and I'm put off a bit by the number of times I've had to support other peoples' 10 installations with niggly problems (but when they work Ok, I don't get to see them!)...
Though while I have all the materials and utilities I need to do an off-line complete re-install (and 'verify') of an XP system (completely valid and legal, OEM key or otherwise, according to the box concerned, just fudging the callback-to-MS bit for practical reasons) to satisfy my own needs to occasionally redo the install from scratch for housekeeping purposes, I'm a bit lacking in the similar utilities to do the same (offline, completely clean reinstall) for my post-XP machines without jumping through the hoops that MS has valid reasons to ask of me, to make sure I'm not a licence-pirate or whatever.
Just had a quick look at the place I last bought my MS OSes from, and it seems they're all out of XPs/not selling them any more. And the sole OEI version of 7 (Pro) is going for more than any of the three versions of 10 that they're willing to dispatch (half as much again as the cheapest of the 10s). Depending on how you're getting hold of your upgrade, you might want to factor that in. Might be cheaper, in the long run, to do a mass upgrade of as much as you could. Though laptops are a bad place to start trying to upgrade from, so...
I have no idea why GIFs would not work on your system. If they're truly GIFs and not actually HTML5 objects based on original animated GIFs, or somesuch, in an attempt to remove Shockwave Flash plugins and objects, etc, out of the ecosystem. Unfortunately, it seems that (as with compilers) a lot of up-scaling efforts to make things use the very latest paradigms seems to have decided it's easier just to say "I'm not supporting old systems" as if there'd be something wrong in maintaining sufficient operability with the older kit.