I'm still using Vista so I wouldn't know, but I just want to point at something regarding old(er) games for the PC. With today's HDD storage capacity it should be pretty cheap and easy (I.E. HDDs themselves being cheap enough, and "easy" to make partitions due to their standard high storage capacity) to partition them so that you'd have both Windows XP and Windows Vista/7/8 as well. And then you'd just switch between OS installations when you feel like playing older games, just as much as you'd physically "switch" from your physical SNES to a Genesis in your living room to play games on the respective systems.
I'm saying this because it seems rather "obvious" to me. If I had Windows 8 and would happen to have old PC games that just won't install or run properly on it I would definitely make a partition with Windows XP (which I still own) and install said "problematic" games on that partition. Additionally, doesn't Windows 8 have any compatibility mode(s) that supposed to help a bit with older software (games too)? Again that's just an example, but I know my GoG.com copy of Beyond Good and Evil does not run properly on Vista (not sure about Windows 7, don't have it, but on Vista for some reasons it has "throttle" issues, game runs incredibly fast, including sound, all scenes skipped lightning fast, etc), but if I enable Windows XP compatibility mode it runs smoothly.
But anyway, my suggestion (if anything) is to create a partition with Windows XP which is sure to be compatible with older games (and vice versa). That is, of course, if you own Windows XP to start with. If you do not own it and don't want to buy it "just for that purpose" then I can totally understand that, but then Windows 8 becomes a potential (or rather confirmed) problem. I would probably just stick with Windows 7 and call it a night if it was the case (I.E. only being able to buy one Windows OS, then I'd go with 7 most likely), but Windows XP should be cheap... I wonder though can it still be purchased today or has it been officially discontinued?