On the N8x0 tapping a GPX file starts Maemo Mapper with that route shown. I store my GPX files in the same folder as the map data base and opening a route in Maemo Mapper goes to that folder and lists the available routes. Building the map data base with Maemo Mapper requires an Internet connection and viewing the target map area. Once built the maps are available locally and can be used along with local GPX routes without an Internet connection. The maps application that comes preloaded on the N900 may work differently. Rather than downloading map tiles as you attempt to view them it may have an install process for loading maps. I can only speak to Maemo Mapper and specifically to the N8x0.