Is MapSource Topo VS 3.02 compatible with the Garmin Montana 600 series?
The Montana should be compatible with any standard Garmin maps - I have not found any problems with mine. Not real sure what "Mapsource Topo VS 3.02" is however. Was this originally distributed on multiple CD's? Or on a single DVD? I have Topo US 2008 now and also had the previous version, which might be what you're talking about.
If so, I would expect it to work fine on the Montana. You will not be able to install the entire US however. The Montana has plenty of memory, that isn't the problem. But it can only access 4,000 map segments and I believe there are over 6,000 segments in that map.
If you get the Montana 650t, it would have a newer version of this same map and it covers the entire US. You can also purchase Topo US 100k (the current version) via download and have the entire US on your GPS.
Then again, you could also download free maps from here. :D