If you haven't given Railworks a look, I would highly recommend it. I've been using RW since it's introduction and in my opinion, it's the best available. My children gave me MSTS when it was first released and I've also tried Trainz. Railworks has great attention to detail and is much more stable than MSTS. Most of the initial issues have been resolved and it's fun to operate.
You might also check out the treads for the Cimarron & Pacific on the Railworks America website. Even though the C&P is standard gauge, it is very similar to the D&RGW narrow gauge lines in the early 1900's.
Harry Adkins