I can assume that you installed DirectX 9 at some point, so I'm stumped,
Yes. I've installed and played several games from GOG on it -- from older ones like Atlantis 2 (Beyond Atlantis) to newer ones like Memoria.
On the 64-bit version of Windows 8 updated to 8.1?
Did NTVDM install on yours? If it did, that could be the difference.
The only other thing I can think of is the video driver, and finding an older driver that runs on Windows 8 will be a problem.
Yes it will, though in my case I can boot to my Windows 7 partition where Still Life plays just fine. I could check the date of the drivers, but I doubt they'd be that different since I set up the dual boot at around the same time.
Microsoft has really made a mess of things lately.
No kidding. They were premature to think everyone wants a tablet OS. And why would they remove the Windows NT and 2000 compatibility? Do you know if NT/2000 compatibility was included in the Windows 8 preview version?