Turning them down might actually improve the quality. The thing is that my poor computer can't even load low-end textures. It's loading a blurry mess.

I was able to actually substantially improve (though they're not perfect, but pretty good) the textures by going into the fsx.cfg file and setting TextureMaxLoad to 12 (it was at 6). It cost me two FPS, but that's not so bad (though it's more than it sounds, considering I get generally low FPS).

When Microsoft Flight comes out, I'll likely be installing it (and maybe FSX, if I can't get any addons onto it) on a brand-new desktop (or really good laptop, like one suggested to me in another topic). I have to do some searching for a good computer, though.  ;D