Well, i think the first question is what are we trying to accomplish?
I know that with my current level of coding experience, it would be much easier to code a "replacement" engine that simply was more aware of the way that new hardware would interact with the game. The original FFVIIPC was written around early-ish PSX coding, at a time when 3d rendering was relatively new. Most PCs were able to work with the programing team's "hacks" - then. Hardware 3d rendering has changed quite a bit, and things like load times, video memory size, and color depth/memory throughput are no longer issues. As a result, 16x16 background chunks are something that a modern video card (which could easily load the entire background as once piece) laughs at.
So, what I'm saying is, I don't think that it would be too hard to write a new engine that follows the design of the original closely. Update it to load the backgrounds in a workable way (that would allow for easy pre-render replacement), allow for increased resolution, and revamp the lighting sceme. Anything much more ambitions (eg trying to "modernize" the game with bump maping, hardware T&L, dx9 calls, and the like would require us to basically recode the graphics engine so entirely that we would also have to recode AI, music, battle, lighting (well, this should probably be re-worked anyways), ANIMATIONS - well it would basically be making a new game. - Which may be a worthwile project, but it's certianly beyond my level of ability/time to put into this project.
But reworking the current code in such a way that many of the obsticles to making this game look the way it should - that isn't much harder than what people are doing now ... hacking a system that was designed before "modern" hardware was invisioned. Come'on guys, this was practically coded for windows 95.
EDIT: Oh, and whatever Windows XP didn't brake, you can bet that Vista will. We're looking at one more year of feasible play anyways - there's no way that this will hold up under Vista.
- Evan