DVD bootable -> CD bootable??

[edward]

Hi,

I have a copy of Knoppix as a bootable DVD.
However, I'd also like to create a bootable CD for use on an older machine that doesn't have a DVD reader (only a CD)

Is this possible? I realise that if I can create an ISO image from the DVD, I can burn to a new CD. But it's this first step that's puzzling me.

Any help gratefully received.

Cheers
Edward

[OErjan]

why not download the cd version?