Hi guys.

Duke 3d is giving me some trouble. It only starts from the "set graphics mode" menu, not the start game link.
With that said, if I run the setup from the start menu the game also won't start, leaving me stuck with 320 resolution...

Someone please help me out!

PS: Blood runs great in 800x600, but unlike duke one can set the resolution in game...

Well, I'm guessing that as you make a comparison to Blood that you are using the game in its own Build engine via the GOG provided DOSBox installation. If you are doing this then try running the setup link from GOG's Start menu entry with administrator privileges and see if that works. If it does then it might be due to you installing the game into Program Files (which is a protected folder in Vista and Win7).

As an alternative, and one which I highly recommend, use the eDuke32 engine to play the game. It is a native Windows application and allows you to play it just like it was in old DOS (but with better mouse-look) or you can improve it with 3D models, high res textures, lighting effects, etc.

Yes I do use it just like GOG installed it, in the suggested folder.
I ran the setup out of the GOG folder in the start menu, but as I stated earlier, the game crashes when leaving the setup.

I would prefer to run the authentic old game and not some kind of modded version if possible.
But I am hoping to run 800x600, as this seems to be the best resolution to complement the graphics of these goldies.

Ok, found a solution.
I use the setup, but instead of hitting "quit setup and start game" I just pressed ESC and said yes to the save setup question. That way the setup did not crash attempting to run the game.
Afterwards I started the game using the "choose graphics" menu thingy and voila, works like a charm!!!

Glad you got it sorted out. Couple of things to note, though:

GOG defaults the installation to the Program Files folder. This is fine in WinXP but on Vista and Win7 it can cause issues due to UAC and DEP. You are much better off installing outside of Program Files when it comes to games.

Also, eDuke32 does allow you to run the game as it was originally. You can have the low res sprite based graphics and no new graphic options such as lighting, etc. It will look just like the original unless you want to turn on the new options. However, eDuke32 has a MUCH better mouse-look than the Build engine, a lot more smoother.

The original Build engine did have mouse-look, but it was very sluggish and stuttery. Plus, you can play eDuke32 without mouse-look should you really want to.