The physical releases of DD had the same rendering options as the demo. With the re-mastered download version of the game, non-Direct3D rendering methods could cause problems with some of the changes made, so were removed from the configuration tool. A few people had issues with Direct3D, though, and solved it the same way you did. There was a topic on Good Old Games' forum about this awhile ago, with a link to the disk version's configuration tool.
