Alright, so I'm running Vista Basic (64-bit) 8 gigs of ram.
Once I dwl'd the game and installed it, I followed the directions listed here -
http://www.gog.com/en/forum/arcanum_of_steamworks_and_magic_obscura/what_patches_should_i_install_on_a_fresh_gog_install
I installed everything as Admin. Set my resolution as my desktop resolution. The game starts up and everything thing seems to be normal, until I get past the character creation and actually enter the game world.
The only thing I can seem to do is open the Esc menu and the options menu. Mousing over my character doesn't do anything, clicking doesnt do anything, etc.
I can move the screen around by mousing at the edges of the screen, but thats all I can do.
Any pro help? Really looking forward to this game 8D
PS - Sorry if this comes across disjointed - is 5am and I'm heading towards bed.

Disclaimer - Pro . . . NOT . . I would open a help ticket with GOG support . . .
Edit: Try Petrell's suggestions (next post) first as the HR mod does cause problems that can be fixed by uninstalling it . . .=)
I have never used Windows Basic so there may be limitations that I am not aware of with that OS.. .=)
I am assuming you also added the -no3d and -doublebuffer switches to the target path on the game shortcut and checked "Run as an administrator" on the Compatibility tab as well . . . and have the latest video drivers installed. This usually takes care of most graphics problems. See the attached image named "switches" to confirm your addition looks the same.
Three other possibilities I will suggest . . .
Follow the link in this post to download RunFirst. It is a small program (free) used to set affinity to one core on dual core systems. If you have a single core system, ignore this suggestion. Of course you would need to add this to your Arcanum path. The example is for Divine Divinity and the path would not apply to Arcanum.
If you are running a dual core AMD processor, AMD has a Dual Core Optimizer available which may help. If you have a dual core AMD and the above doesn't help follow this link for a download link. I would try this before limiting the memory but ONLY if you have an AMD CPU, it will not work on an Intel system.
Some ppl have fixed game problems with Win 7 / Vista 64 systems by limiting the memory available to the system while playing. Attached is an image which shows how to do this. Make note of your existing setting prior to doing this as you will want to change it back when not playing the game - assuming it helps. Image name is "LimitMemory" I would try this only if all else fails.

Haven't heard about that one. If you have installed the game outside program files and have the -no3d -doublebuffer set in your game shortcut, the only suggestion I can think of right now is to uninstall High Res patch (using HighRes.bat) and trying to run the game without it. If game works then you could again try to reinstall the High Res patch but using lower resolution (how high have you set it now? I have set it to 1024x768 while my screen res is 1600x1200, the default game resolution is 800x600).

Analyzing the info you have given, my suggestion for a solution would be to get plenty of rest and participate in the game play . . .=D