I found this while trying to find a widescreen fix: http://heroescommunity.com/viewthread.php3?TID=31525&pagenumber=3
Basically allows you to play HOMM3 in any resolution you can support but has anyone seen this and been able to apply it to GOG's version of HOMM3?

Good news and bad news...
Bad news: The posted files only work with HoMM3 Shadow of Death 3.2, and the HoMM3 Complete version available on GoG is 4.0. I could get it to launch, but a CD check appeared :(
Good news: The posted files do work with the "Wake of the Gods" .exe, even when installed on the GoG version (more information on this mod is in a sticky post in this forum). If you download and install WoG (allinone_358f.zip), you can then use the HD tool with that. Note that WoG will add some unexpected features, even in the vanilla campaigns... and it replaces the Shadow of Death campaign with its own.
Better news: It also works with the Heroes 3 "Tournament Edition" mod (details here). This behaves a bit more like the vanilla game, but it's still a bit strange.
Screenshot of WoG in 1280x1024 attached. To be honest, I'd rather play full-screen.

Version 2.0 was just released. There's a GoG compatibility pack that you can get with it that works great, so all you need to do is download both that and the HD patch and extract them to your HoMM3 directory. If you're on Vista or 7, you'll need to right-click on the setup app and run it as admin, but that's the only extra thing I had to do to get it working.
Edit: After looking into turning this into a WoG package, I found that if you want to use it with WoG, you have to have WoG installed before installing the HD patch (or you'll get errors when trying to run HD WoG) and then you have to run Heroes3HDSetup.exe twice (or you'll get resource errors when trying to run the HD version of the base game). I left a message for the author on the forums where he posted the release, so hopefully he'll look into it. If you don't use WoG, though, this doesn't really matter, since the patch works fine on just the base game alone.

Neat! it really feels great playng big maps.Actually now im more interested in playing big maps :)

Thank you! I will try that soon, as I uninstalled WoG a long time ago. Nice add-on to the game, but it's not HoMM anymore to my taste...

Okay, for an unknown reason, Kreeblah, the website you mentioned only works for the GOG add-on. I mean, when I click on main file, nothing happens, but when I click on the GOG compatibility add-on, it works. Odd. Do you have an alternate download location?

It looks great on screens. It would be great if this mod could be added to GOG release.

I tried this with the GOG version of HOMMIII complete and love it. I have it installed with XP and WIN7. You have to run the HD setup as Admin in Win7, but that's all. I have a 1080p screen, but I feel that's a little too big as it makes everything on the screen too small.
1366x768 (720p) is the best resolution IMO.
One thing I wondered about this is whether the AI can also see this much area? When we explore, the map get revealed and when you have the patch enabled you can see a lot more. What about the AI players...can they also see such a wide area, and thus see your heroes and towns etc?

Easy. Really easy. Like butter.
The one link provided above and later in this sentence clearly has everything EVERYTHING needed.
Step One: Install GOG version of HOMM3 Complete.
Step Two: Using link above, click "Download" from the left column and download "Main Files". This is the Hi-Res data for the mod.
Step Three: Unpack the "Main Files" into your installed GOG version HOMM3 Complete folder. This means you have to remember where you installed it or what the path is.
Step Four: Using link above, download "GoG_Complete" file.
Step Five: Unpack the contents of that file to the same place as in Step Three.
Step Six: Run Heroes3HDSetup from the HOMM3 folder, choose resolution, apply, and launch.

thank you... got it working!

I didn´t know that HD mod even exists! Thank you guys, really big thanks!

P.S: HoMM3_HD_2.52f works fine with Czech retail version of Heroes of Might and Magic III Complete.

If you are new to HoMM 3 I'd recommend you to stay away from WoG . It's very good as a tool to build some other mods on later, but it goes too far away from the original game.
I really like HoMM 3 in it's 800 X 600 resolution, but it's good there are tools for those that don't.

This is a great find!
Was going to post it, but the thread was already in place.

HoMM3 HD 2.65f version is out: http://sites.google.com/site/heroes3hd/eng/download

Working perfectly for me, Win 7 64 bits, geforce drivers v260.99.

Does anyone know something like this for HOMM II?