Oh wow.. where to start? i don't know if they are on PC but I played Grandia and Grandia 2 like I have never played a game before.. Grandia on PS1 and Grandia 2 on PS2.
I've got no interest in Final Fantasy, but the story in Grandia swept me away.. it's a vision of a whole different and wonderful universe. LOL! I'm getting carried away

but they are beautiful.
Strangely, I haven't really played any adventure games on my PC yet (though I've had a PC for 3 years now). From my PS1 days, I played Wild Arms, Harvest Moon (fab game), Legacy Of Kain, Alundra, Alundra 2, and Grandia of course.
If you like strategy (or in my case faffing about with the game set to "easy" mode) try Civilization II (crude graphics but you'll be playing it untill next spring) or Age Of Empires or Sim City.