Head's up on Sierrahelp, there is an updated patch for Mask of Eternity, that claims to be 32/64 bit vista/win 7 comptible. IT also installs the Glide wrapper/emulator for improved graphics.http://www.sierrahelp.com/Files/NewInstallers/KQMaskSetup.exe
Don't know if it works, but it might be worth a try for anyone not willing to go out and buy the game on GOG.
I bet whatever the patch does, probably works off whatever GOG did to get them to run.
Here is my technical guide for getting past the common problem/bug areas in the game;
The windmill is an area that often locks up during the cutscene of the first henchman appearing. Turning off all extra graphics (no shadows, play in software mode, etc) will raise the chance of getting past the cutscene.
Note that Dimension of Death is particurarly buggy, especially in first person mode. Make sure to save often, as it can lock up at any moment (especially around the edges of wide open areas).
The Realm of the Gnomes suffers from lag, first person can alleviate it somewhat, however the game is more unstable in first person mode and may crash. The weapon, apothecary and armor shops are another area that may potentially lock up. Try turning off all the extra graphics and changing resolutions if you have a problem.
The Weirdling Weapon Shop is another particularly buggy area, that locks up after the initial cutscene. Best way to get past it may be attempting to enter the building while walking backwards, or trying to come back after doing other things in the land. If that doesn't work use a save game past the cutscene may be the only possible way of avoiding it.