Sounds like you made the disc properly. I have no experience with Nero 7 but absolutely no reason to think that there could be any problem there.

Your hard disk configuration is not a problem. Knoppix does not even need there to be a hard disk to boot; you could unplug your hard disks and I expect you would still have the same problem.

Have you tried the knoppix dma cheat code mentioned in the other thread that you referenced? The version of Knoppix that you have has DMA off by default, but some systems need it on to access the CD properly.

If that's not it you may need to read the cheat codes section of the wiki and try other cheat codes or even combinations of cheat codes. You may also wish to try the failsafe code (not the way that you want to run Knoppix in the end but you may learn something in doing it) or boot using the expert code and step through all of the hardware detection questions and take notes about your answers. When the boot process fails try again and change your last answer.