JinKazaragi: What version does your game-installer have (you can see that in your library)?
As soon as a patch is released it also is included in the games installer, meaning if your installer is the 5.1.1 version your don't need to install the patches.
Book728: The game installer under OS in My library say 5.1.1 (Gog-21) - Is Gog 21 a number Gog gives the parts of the Dreamfall chapters game? I thought because patch 5.03 was a higher number than patch 5.1.1 that 5.03 was what I would need to install. I haven't installed Book 5 yet, so I guess I need to install patch 5.1.1 when I install the game since it was the last patch made? I have played Books 1-4 and they worked out ok, but I am a bit confused about the order of the patches and what they include, etc.. I am using 64 bit BTW.
The "GOG XX" ist just another way to neme the version of the installer or the patch (GOG 21 = 5.1.1).
If you download the intaller ot the game now and use the you have the newest version which includes all books.
If you already have installed an older version on your PC you need to apply a patch.
5.1.1 is newer than 5.0.3, 5.0.3 adds the fifth book and 5.1.1 seems to fix a few bugs.
If you're not sure how to do it or in which order to install the patches (usually it is mentioned which version of the game is required to use the patch here it's not unfortunatly):
Deinstall the game (you get an option to keep your savegames) and reinstall it with the new game-installer and you have the newest version with sll 5 books.