Bootable CD

I'm pretty sure that as long as there is a system folder on the disk it is bootable, you might want to throw some disk utilities on there too. Does anyone know how to specifically make an OS X disk?
I've tried to burn a cd with my old 9.0.4 system on it; this was before upgrading to Mac OS X/Classic 9.1.

The cd would either only boot half way and then cause a crash or just plain refuse to boot.

So, I think there could be more to it than just copying...