Finally downloaded all the files.......then opened 3DEM,  chose an area I think is Olympus mons, and loaded the first .img file, et voila!
http://cal3d.com/vue/OM1.jpg

I don't have time to do more for now, but that's the first time I've been able
to get at least an image from 3DEM......will export the USGS ASCII DEM later
for VUE.  I'll see how Carrara & Bryce handle it, too.  

Thanks Shawn for all the help.....I'd still be knocking my head on it with out it. :blink:

There are so many sites, file/data types, you almost need to be an astro-physicist
to figure it out.