After my zumo died I recently bought a Montana, thinking I could also use this unit for other outdoor pursuits. It came preloaded with Topo 100k. I drew routes on Mapsource (I have Basecamp but haven't really learned it), loaded them to my Zumo, and it calculated routes I could follow on my bike. All good. If I needed to find food/lodging, etc, it directed me turn by turn. I have read a lot of the Montana thread here, and my understanding is that I need another program, either City Navigator or Topo 24k, to calculate routes from my waypoints. I have an old City Navigator CD that the PO gave me with my first ZUMO, but I don't have an unlock code for it. It looks like I need CN to calculate routes on Basecamp. I have a few questions. I appreciate the help I always get on here. 1. Is CN good enough to route on dirt and FS roads? 2. If I buy CN on MicroSD, can I install it on my laptop, or should I buy a CD and install it on the laptop and MicroSD myself? 3. Or would you recommend Topo 24k, which appears to be a regional map? Can this Topo calculate routes? Thanks so much!