Thanks for the replay! It's a custom-made, proprietary HW (basically a signal tester device), not a massmarket one. Its drivers work only on Win98 and Win2K.
I know that list but I just cannot believe that only this few, out of the combinations of the hundreds of CPU and motherboard models, are working. I already checked that list and I have access to many mobos but these are, unfortunately, not among them. Sure, I can find them second-hand if they are really the only ones but I still hope someone had success with other model that I might have...