It took me a while to figure this out. When you have GPS enabled and are connected to the GPS, do Auto-Center->Lat/Lon. This will make the map keep refreshing as you move. As an alternative, you can choose Lead, which will keep your position dot closest to the edge of the map that you are coming from so that the way forward occupies most of the screen.

In conjunction with that, you can also select View->Velocity Vector. This will extend a bar out from your current position that points in the direction you are heading. The length of the bar is proportional to speed that you are going.

If you don't see these options, you may have an older version installed. Mine is 1.4.3-3 for the n800.

-- rhackenb