Try it without patches ;)

I won't :) I don't want to kill this good first impression !

Hello everyone (my first post around here)!
I played Arcanum long time ago and multitude of bugs and general lack of balance threw me off.
Now I bought it again (it was great game after all, I would love to finish it) but I am unable to install latest UAP (link from this thread). It says that it can't open Arcanum.exe for writing. File is not read-only, I have vanilla GoG install. Any ideas? Help much appreciated!
PS - I just installed HQ towns, but still can't install UAP
SOLVED - On Win7 patch detected installation folder with '\' on the end. After removing '\' it installed smoothly. Duh.

There's also Carcanum. Not sure about how good of a mod it is.

Installed everything but the hi-res patch, as 800x600 is fine to read the text and see the characters, at too high a res on games like this and Fallout 1 and 2, you might as well have stickmen walking around for all you see! With the Fallout'sI run them at 640x480 on my 24" widescreen and it looks great! (I have an auto sizing option on my monitor, so any resolution will be full screen!)

When you install the widescreen mod it fixes the text size for you. I'm not sure how legible it is because I get a CTD whenever I try to install it though. Reading the other posts, I'm the only one with this problem though. Oh well, off to fix it!

I agree at or near 800 x 600 seems about right. I would mention that you could install the HR patch at 800 x 600 in order to take advantage of the optional "compact" UI . . . having the UI nearly gone is nice and helps with the immersion factor. F10 key switches from standard to compact to standard. Attached an image for comparison . . . =)

Also setting resolution to some widescreen resolution on widescreen monitor prevents streching distortion (everything will look bloated unless you use "fixed aspect ratio" setting)and allows use of whole screen instead of black borders on left and right of the screen. High res patch also supports windowed mode.

You don't need a mod for the compact UI. Just use the -fullscreen command line argument then toggle the UI in game with F10.
Here is a list of all command line arguments if you're interested.
http://www.terra-arcanum.com/phpBB/viewtopic.php?t=15208

I am running it at 1280 X 1024 and it looks great. I tried it at 1920 X 1200 but things were a bit too small.

You should also consider using one of the level cap removers.
IMHO, the best (balanced) one is this:
http://www.rpgcodex.net/phpBB/viewtopic.php?t=28859
And yes, it is compatible with all mods and patches.

So I downloaded the latest version of of the Unofficial Patch, and when I was trying to install it I keep getting the message:
Error opening file for writing
and then the location of Arcanum.exe on my hard drive...
and it gives me the choices of retrying, ignoring, or aborting the installation...
Does anyone know what I should do?

Run the patcher as Admin.

That worked! Thanks!