Why would it matter whether it's a CD or DVD drive though? Surely they will all boot the OS 9 CD? (at least the CD-DVD-RW one in my G3 does)

Also, did we ever get to the bottom of this issue of booting an older version of OS 9 after having installed Tiger - was that an issue on just one Mac or something that happens every time? I just can't really see what Tiger could do to stop older versions of 9 from booting. Also I definitely booted from a 9.1 CD after having completed the first half of the Tiger installation (the half that installs the core of the OS), though haven't tried since completing the installation.