Thanks Tarbat and Alan. The link works to the FAQ but the Flickr parts of it don't display.
I have extracted the drivers to the PC desktop but I noticed they are zipped and maybe this is the problem because I've not unzipped them as when I follow Alan's instruction I get the message that the files don't exist. So I assume the sequence of events is download (zipped), unzip to a location then install from the unzipped location to C:\Program Files\AirNav\Drivers. Then plug in the USB?
Thanks
Wayne