This actually worked, thanks a lot man. If anyone else has this issue, the actual steps I took was:
1. Install the PS DDS plugin for Mac, found here.
2. Open both the "Earth_NRM.dds" and the "EarthColor.dds" with photoshop.
3. Save as, Replace original, & with the settings: < Format: DXT5, Check "Mipmap", Filter: Mitchell >
The "Mipmap" option wasn't checked originally and simply re-saving didn't make a difference, when I tried checking it it seemed to do the trick. - I must say that I don't have a clue what I'm doing here and I've yet to fully test it out in game, but it does seem to be working fine now.