Okay, I haven't seen any comments regarding this, but in case anyone is having trouble as I was with the GOG version, I've found the solution. The link provided for the GOG downloader version does not work,
at least it didn't for me. Whenever I tried to load any of my saved games, they were listed as invalid. When I checked the menu, it looked like Books 2 and 3 were not there, so I tried downloading the DLC for those books and installing that. When I did this, my saved games would load, but the characters had completely disappeared.
So, it appears what you have to do is download each small file
individually (if you want the version without the Galaxy addons, go to More, and select Classic Installers), including the DLC Download for Books 2 and 3. This is much more frustrating and time consuming, but it's the only way I was able to get it to work. Afterward, first install the game itself, and then, make sure to install the DLC, so Books 2 and 3 will be added as well.
After doing this, my saved games were able to load with characters intact. I spent all day on this, so I'm glad I at least got something out of it for my trouble.
Hope this helps if anyone else runs into the same problem I did.