Why would your computer being brand new and having the latest version of everything help you to play a 15 year old version of a 20 year old game? I'm not saying you should have expected problems straight away, but the newer the computer the more likely you are to run into problems with old games.
Wrong. Windows 8.1 is certainly worse than 7 in this respect, as Microsoft seem to have broken the DirectDraw emulation necessary for a lot of old Windows games to run. Due to some change between W7 and W8, a lot of DDraw games run at a crawl, sometimes as low as 1FPS. It's been a few years and Microsoft have shown absolutely no inclination to fix it whatsoever and until they do, Windows 7 remains better for old games than Windows 8(.1) is.

Wrong. There is DDraw emulation in Win8 - but not in older Windows. If you knew what you were talking about, then you'd hardly claim DDraw emulation in Win7. Furthermore, it works just fine. No games that use DDraw "running at a crawl", good example is Fallout 1 and 2, both work like a charm on Windows 8 and 8.1

If you knew what you were espousing, you'd know that.

I said a lot, not all. Try playing Septerra Core or Desperados some time. You'll notice GOG doesn't list Windows 8 support. The point I'm making is that Windows 8 has noticeably worse DDraw support than Windows 7. Your claim that it's the best OS for old game support is BS. I'm not claiming that Windows 7 is the best, it's just better at playing old games than Windows 8.
I'm speaking as a Windows 8 user by the way, I'm not some guy hugging his XP machine and desperately trying to banish anything newer.

Hi. I know that this is for win 8 issues, is there another for win 10? I bought Myst and Ur before I knew about galaxy and have had no luck with them.

Uru runs just fine. As for trying to run a 15 year old game, there's a reason why they remade the remake.

Try running Urusetup first.