I think for many ppl this site was already in their favorite sites :)
At least for me.
ftp://ftp.visibleearth.nasa.gov if I got it correctly. And i've tried to make an earth 43k, but photoshop wouldn't let me make a file bigger than 30000 pixels.
Then tried it in the gimp, it was possible, but would create a file that was 3500 MB. A bit too much for me to work with. So yeah, you'll need these very specific tools for editing these files, without loading them first.
Pixel seems to have them. But i wouldn't think the 43k texture adds a lot to the 16k.dds texture. I was able to load the 400 MB file. And found that the quality wasn't all that more stunning than the 16k file.
Besides, there isn't any graphics card that can display this map properly.