I have the BU-353 running on a windows XP machine. When I use the GPSINfo application I'm able to see the the lat and long, speed, and direction, however all these numbers keep changing even when the GPS is sitting on a desk not moving. Occasionally a speed of 1km/hr is even noted while the gps receiver is stationary. I've used the unit with Quantum GIS, and found the same issue there, with the GPS actually displaying a track while standing still. The distance between fixes can sometimes vary up to 6m.
Why isn't the fix standing still when the unit is not moving?