The 2Gb card is for storing map info. Older Garmin GPSs had internal memory. Most of the new ones now have a removable map card, particularly the HCX models, in fact you can buy the cards preloaded with topos, blue charts or whatever. For example, my current Rino 130 has 24Mb of internal memory for maps, that's enough for only a section of the Alaska topos. With the new memory cards it should fit the entire US Topo CD (since you can buy the card preloaded on a card I'm assuming 2Gb is enough for all the maps).
As far as I can tell the base map is burned onto the main board (prom chip) and cannot be removed.
I love these things. I won't leave the trailhead without mine anymore. With the maze of trails, siesmic lines, swamps, lakes, creeks and such around here it's too easy to get turned around and miss a turn back to the truck especially when the weather moves in and the land marks disappear.
The built-in radio is a great feature in that you can broadcast your position to your riding buddy or poll his Rino for his location.
I want to find a headset to install into my helmet so we can communicate while on the trail. Be great for oncoming traffic on those blind curves to warn your buddy. Working on it.
