Found out about this by just randomly surfing around the net. It supposedly fixes a lot of the problems that plagued the original Heroes 4 game.
http://equilibris.celestialheavens.com/eng/changes.html.
I am also linking this here just in case Heroes 4 gets released on GOG. :D
Enjoy and I hope it works!

Yeah, this is a great modification for HoMM4.
I wanted to post about it here too, but I didn't do it because it isn't released here yet (if ever) and because most of people will say that HoMM4 sucks anyways :)

Well I was hoping to help those who did not know about the mod and maybe ease the suckage of HoMM4 :D.

The less is game Heroes 3-ish, the more it sucks.
At least this is how I see it from the reaction of Heroes 4 haters. And since Equilibris only balances Heroes 4 and doesn't make it more Heroes 3-ish, it will still suck :-/

which doesn't matter to me, as i love both HoMM 3 and 4 (and even 5) !
Thank you for bringing this great mod to my attention ! And to see that it's compatible with my french version is a great plus !

Glad to hear that! Enjoy the mod!

well, the installation went perfectly well and, what a surprise, the new .exe acts like as noCD patch, so I don't even have to worry about scratching my originals !

Yes, Equilibris is quite a good mod.
One of the little tweaks I especially liked was what they did with the Necromancy skill: on Advanced level, you can get Zombies, and on GM level, you can even get Bone Dragons (provided there are Dragon corpses to raise). Also, IIRC, it gives you the possibility to set what you'd like to get (from which you already have the skill for).

bump

The other Heroes mods got stickied, can I get this one stickied as well? Thanks.

Should be stickied, I agree.
Equilibris Mod is a great mod for Heroes IV, which I play all the time, also some excellent fan made maps out there.