Engerek01: The Moddb widescreen mod
worked perfectly for me. For those who are confused ....
1. Download The Moddb Widescreen mod
2. Open Lionheart game folder.
3. Here you will see a huge Data.dat file. Unzip it to /data folder. (7-zip program worked fine for me)
4. Delete Data.dat OR change its name (Forexample to dataold.dat)
5. Unzip the Lionheartwidescreenpatch.rar file into game folder.
6. Run "LionheartWidescreenPatch.exe" which is now inside the game folder.
7. For my laptop I choosed 1280x800 resolution and click Apply. It only takes a few seconds.
8. Play the game :)
I did this on vista and my computer from 2007 worked just fine. I hope this helps for future.
EDIT: I removed the "you can continue your old saves" part because it obviously corrupts your play.
I checked the executable of the game to run in Win XP SP2 compatibility on my Win 8.I get this message and then no resolution to select: