I have TN Pro V8.51. My laptop isn't mounted, but I do place it in the seat next to me for routing on occasion in my vehicle when exploring new terrain. I'm not expedition explorer, but I do spend 5-6 weekends and maybe one long week a year searching out remote trout ponds and streams to get away from everyone else.
I have a delorme PN-60 GPS on the dash that provides a signal to XMap so I can track my current position on the map (overlaid onto the DeLorme Data, USGS quads, or color imagery) in 2D or 3D.
Delorme's vector roads are routeable, so I can create a route and get turn by turn instructions, with voice prompts (that I cant hear very well, my hearing and a laptop limitation).
Then I can also put the exact same data onto my PN-60 GPS - all the map data (imagery, delorme data, and USGS quads), and leave the truck and go into the woods on foot.
For $30 I have the delorme map pack subscription, I can download color imagery and USGS quads for the area I'm interested in to my hard disk, study the imagery and place waypoints for places I want to visit, then route to them. I taken paper maps, scanned them, and imported and georeferenced them and navigated using them as well.
As far as I can tell TNPro is mapping software. Delorme Xmap (or TOPO) is both navigation and mapping software as they support many navigation-specific features like the routable vector base data and good routing tools. By routing I mean set a start and stop point on roads or 4WD trails and XMap finds the best route along those roads based on your preferences, you can place vias to force the route wherever you want. You can also create direct routes between waypoints, which is all I've been able to figure out how to get TNPro to do (no road routing.
For $259 plus the $30 subscription I have everything I need for all of North America. Works for me anyway.