Well, a couple of things seem to be potential culprits. First, it's been a while since I used this node, but in most cases when you specify an image file name you need to specify a specific file rather than just a directory. Do you get any file loading errors in the errors and warnings window? It's possible it's reading all the data in that directory and tiling it, which I believe the node is capable of, but I think normally that's done by specifying one image of a set, and it will load the rest. I'm not sure that specifying just the folder works.
Also the 128MB data is higher resolution than you'll probably need from orbit, and you'll need more of the files (and thus more memory) to cover the entire planet. You might try starting with the megt016 data (32MB) instead, at least at first.
- Oshyan