I didn't see any computers running this OS during my trip to Pyongyang. I saw a few machines running Win2k and one that ran a bowling alley ran Win3.1. Comical stuff..
I commented on another North Korea post here on Hacker News a while ago, where I also posted the URL to the photos, if anyone are curious. It even had IP addresses set and some sort of network (not Internet) access.
Koryo Tours is one that I took a few years ago.
http://www.arrl.org/news/p5-3z9dx-concludes-demonstration-op...
But to reiterate, you can just book on a tour. There's no problem or difficulty doing it.