No offense but have you posted this on the GOG forum?

I posted there that 11 June and still no reply, and I also see that game don`t like radeon`s at all, and I read there is a solution to install Windows Vista but at my rig that windows is is slow and I don`t have enough ram there for him.

I remember this game has lots trouble with non win9x graphics drivers,
like how minimap aren't shown unless you specfically force it use certain Anti-Aliassing modes in graphics-driver control panel.
or performance degradation if you switch into another task then switch back to the game.

I changed Videocard to Gigabyte GeForce 4MX 440 and I used 93.71 driver and game is completely smooth, I also tried that game on my main rig (Pentium Dual Core E2180+GeForce 8600GTS) at win7 x64 with 341.44 driver and also there Battle Realms is smooth, I see somewhere that game also have don`t slow on Intel HD integrated graphics. I tried also with Radeon 9600 6.4 driver and game is also slowing, when I tried with Vista 10.2 driver, there game is smooth, perhaps problem is somewhere at XP and ATI driver`s. And I tried Omega Driver 4.8.442 and also I have slowdown.
I installed 5.12 driver for Radeon 9600 on XP SP3 and Battle Realms is smooth all time now on that videocard 😊