I recently have been dabbling with my new art tablet and texturing Morrowind. I discovered that if you leave Morrowind running and "Alt-TAB" out of it, any game textures you alter while the game is running in the background will load into the game when you "Alt-Tab" back to Morrowind.
This saves tons of quality checking time since you can just pop back and forth between your art program of choice (GIMP for me) and Morrowind. And I also imagine, people could check out mutliple textures packs this way if they wanted.
I don't know if this is common knowledge or not so I thought I'd share it just in case it isn't.
Hope someone finds this helpful.
Pinkertonius