I have a Duron 1.GHz, 768 MB ram, with the Asrock k7s41gx mobo and Knoppix works fine on it but If I remember correctly, I did have to use a cheat code to make it boot up. Try the cheatcodes:
knoppix noapic dma
knoppix noapic dma noacpi
knoppix noapic dma noacpi acpi=off