Boyd,
There isn't new software out that does what Terrabrowser does so that is what I use. If there was I would use it. All of the new Mac software is pretty much useless for stone searching or for that matter doing anything. Google Earth is the best I have found and that is marginal at best especially displaying tracks. In any event, Microsoft has the servers back up for some reason so I was able to complete the downloads for USAPhotoMaps in the event the servers go down again and I can't use Terrabrowser.
The cache on Terrabrowser does not work with 10.6, so all the maps I have viewed in my computer with it that are in the cache are useless. So I booted into 10.4 on a Firewire drive and the cache works. So I have downloaded 500MB of maps at every level except full zoom. For some reason Terrabrowser requires you to view every location at full zoom to save it. This would take me years to do so I spent hours doing it one zoom level up.
So I am in better shape now than I was a few days ago mainly because of tips from Bob and Al.
Guy