That's mint! I may be using that program soon.Have you ever tried RPG Map Editor 2? It's a free (well, a "pay what you want") program with which you can make, in my oppinion, quite decent looking maps, with lighting, darkness and fog effects. It is very simple and user-friendly (you will be using it in five minutes) and, while somewhat limited and not perfect, allows for very atmospheric and interesting maps.
Here is an example of what you can do with it (the Medea, my group's Nostromo-like ship):
And here is a link to the RPG Map Editor 2 download site.
Also love to see you using the torrens.