What is wrong? I'm trying to load knoppix 3.4, but i keep getting the "non-system disk" error. I've burned my cd using Nero 5 with 3 files:

KNOPPIX_V3.4-2004-05-17-EN.iso
KNOPPIX_V3.4-2004-05-17-EN.iso.md5
KNOPPIX_V3.4-2004-05-17-EN.iso.md5.asc

Is this correct or am I missing something?