The Dark Souls release for the PC is a rather sloppy port from the Console Version. Having played the Original Dark Souls for both PS3 and XBOX360 I can confirm this. However a Fan of the Game released a fix that will allow you to boost up the resolution from the native 1024×720 to modern PC game resoltions.
The fix can be found at http://blog.metaclassofnil.com/. In oder for the fix to work, you need to disable the ingame AA.
Prepare to Die in High-Res 🙂