The game is so dark I can not read signs or see very well. Here are my stats.
Card name: NVIDIA GeForce 6600 GT
Operating System: Windows XP Professional x64 Edition
Processor: AMD Athlon™ 64 Processor 3200+, ~2.0GHz
Memory: 1024MB RAM

Go to Options, and check your video settings. You may just have the brightness down a bit.
Operating System: Windows XP Professional x64 Edition
Processor AMD Athlon 64 Processor 2800+ 2.0 Ghz
Memory: 1024 MB

as i'm playing on a laptop here, it was quite dark for me as well; gamma up, doesn't look too bad.

Even during the day? Must be a hardware issue.

In game....
At night, I burn throught the torches. I also have CE night eye and light shields but they're not as good as a torch (go figure).

If you'r video card can do it you can adjust the brightness beyond what the game/your monitor will let you.
I have a 9800 pro and in the control panel you can turn on hotkeys. I have binded alt+f1 to up brightness, alt+f2 for contrast, and alt+f3 for gamma. my monitor is old and not very bright anymore but this trick works for me.

may have some glare too, I have to have the brightness on full to see anything in a dungeon when I'm playing during the day.

I ran into a problem like this before, but id your game on windowed mode? toggled it to that and it was pitch black... hope that helps