My wife wanted own Garmin for Geocaching and I thought I would try a Garmin Oregon 300 as I was using a Dakota 20. The best deal sit had an even better deal on a combination topo 100k, 4 GB microSD card & Oregon. I was hopping the 100K topo had routable features like the 24K maps which topo 2008 did not have. Topo 100k maps will only draw straight line routes. I can't find any difference between topo 2008 and Topo 100K except you don't have to convert Topo 100k from PC to Mac format.
The reason I am posting is BaseCamp will not show Topo 100K map for selection until you remove Topo 2008 from the map folder.
After warning everyone, about installing new maps causing loss of my waypoints, tracks, & routes, I did the same thing again. I was running 2.1.1 beta and the install DVD Installed 2.0.x without warning. When I unknowing launched the old version it told me my data was incompatible but my only option in the dialog was ok and it erased my data again. I replaced from time machine not thinking much about it but if I had not had a backup, I would have be upset.