This is a mod that replaces the most important models in the game with higher res ones. For first time ever, this mod is able to do this on the field screen as opposed to only when a character is in battle. It also replaces more models than any previous mods combined.
More info:
Qhimm Forums, further down the page
A great FFVII soundfont (the best, IMO) that makes the music sound just like in the PSX version: Here WARNING: THIS SOUND MOD IS UNSTABLE!
You will need the following program: LGPTools 1.60. Then just follow readme included with the mod.