When in the game, parts of creatures and other objects are not seen. It looks like the background is partially in front of them. Why? WHY???

I have 1GHz Duron, 256 RAM, Radeon ve, Windows XP.

the most likely answer is PoR is REALLY buggy.

I think if you adjust character occlusion on the options screen that will go away.
I also turn the combat speed way, way, way down so that the game truely is turn based. It takes longer but, gives you more of the PnP flavor.