The windows version of Dungeon Keeper.
I have never had any problem with the Windows version on XP on a modern system. There have been some problems with Vista and Win 7, but there are work arouns that seem to help a lot of people.
ANyway, there is always the DOS version of both DUngeon Keeper and the Expansion,and they work fine under DOSBOX, so it is not really a biggie. BTW the DOS and Windows version are exactly the same.
You can't use the 3D acclerated version in DOS, but you are not missing much (the graphics are only slightly improved) and most modern Video cards don;t like the acclereted version anyway.
1. The 3D accelerated version does look significantly better. I think it will run in a higher resolution too.
2. While the DOS version does run through DOSBox, it doesn't run smoothly, at least not on my system. It's playable, but not too enjoyable.