I have used Nav Box linked to a £100 Garmin eTrex, a moving map GPS for about £170 if you already own the laptop. A mate and myself did a VFR route and checked at various waypoints along the route and found the software to be extremely accurate so top marks to Nav Box.
The instructor we used for a Jersey checkout was in shock when we pulled the laptop out in the aircraft and set it up - he had never seen it before and was telling all the others afterwards. nice to get one up on an instructor every now and then :o)