Windows 2000 works with it. Also tried SP2, it still didn't workit is a Realtek AC97 chipset? from that pentium model I think it is arround the same era as the duron 1000 I restored to working condition yesterday mine is a gigabyte 7VT600. Did you check is the onboard audio is enabled on the bios? I had to do the inverse as you whit the realtek my mother board I has since it cause conflict whit my soundblaste live 5.1 on windows 98