and there is no external storage to be able to add an SD card for maps.
Etrex takes 2GB (max) micro SD card, in the battery compartment. It’s where you store the maps you download to the unit, or you can buy maps already on microSD (can’t use there on Mapsource like the DVD maps though).
but the etrex isn;t designed as a satnav for the hills, its just a basic unit.
[Dragnet] I’ve never needed more [/Dragnet] (although a Dakota and £200 of OS maps would be nice).
I do what you suggest and use MemoryMap to plot a track, then no matter what suprise singletrack I find I know where I am in relation to the line on my Etrex. For road stuff, the Etrex is all you need. For offroad, I’ll probably have an OS print out in my pocket just in case.