I was excited to download this old game. Used to love it. The problem is the dialogue just hangs around too long afterwards and the rest of the playscreen is blacked out. The interface works (exp bar, inventory, maps, recipe lists, journal etc.). I tried uninstalling and reinstalling. And i changed the compatability to every OS from 98 to 7, XP and all.
While my pc is a little old (ATI radeon 5570, i think), I'm not savvy enough to figure this out. Please give this simple guy a hint.

First question: did you install through the Galaxy client?

For reasons unknown, back during the Galaxy alpha I found that it was installing a different version from the regular installer: Arcanum.exe was 674KB rather than 1960KB, and it failed on my machine with symptoms that sound like yours.

http://mantis.gog.com/view.php?id=1159 was one of the many tickets GOG staff closed without investigation because it was submitted when an older version of the client was in use.

Just chiming in to add that I had a very similar problem with the Galaxy version as well. Interface seemed to work, but everything on the main screen apart from the dialogue was blank.

Downloaded the 'normal' version via the site and so far it seems to run fine.

I have the same problem

You must add two run parameters in GOG galaxy version (in shortcut properties) as is written in this problem solution:
www.gog.com/support/arcanum_of_steamworks_and_magick_obscura/graphical_and_launch_problems

I think I tried those and saw no difference, but maybe Galaxy's version has changed since then.