I just wanted to say, that it's a pleasure to work with Terragen!
I recently had to buy a new computer, the old one died. Now I have an Intel quadcore and 16GB RAM, which is a quantum leap for me since my previous machine had only 3GB.
I am working at a space scene at the moment with the earth in the center of the image.
I got three image maps with 43k px resolution each. I have an old Photoshop version installed, which is a 32bit program, so no chance to open one of them. Then I tried Irfan View. I could open one of the files, but it was only 21k, when it was loaded.
XnView didn't work either, and GIMP opened it and then refused to respond.
In Terragen I could load all the three maps into the appropriate Image Map Shaders, and it worked like a charm.
Incredible piece of software!!!!!!!