Coincidentally I'm working on Vesuvius now, but not using DEM or TG2
. Had a look for some DEM a few weeks ago. It's not that easy to get hold of and isn't particularly high quality at all. In the end we chose not to use Terragen for this project so I've created it by tracking a heli-shot of Vesuvius and then creating geometry over the nulls PFTrack spits out.
I'd be interested to hear of any DEM you do find mind.