DKS (like almost all games) is a 32bit application, and as such it cannot address more than 4GB in total - this includes memory used by your OS (or it couldn't make system calls) and also your graphics memory. So the actualy ammount of memory the game gets is significantly less than 4GB.
2GB less.
Even on a 64-bit system with eleventy billion gigabytes of memory, a 32-bit process only gets 2GB (or 3GB if you fiddle with the executable). Something I sometimes find myself forgetting, though one of the reasons I upgraded to a 64-bit system was so I could have a bunch of memory-hungry applications running at once: previously when using 32-bit Windows XP, the system itself was a bit too limited as to how much memory it could use in total. But I think someone might've just said that. I wasn't paying attention. :o
