booting from older cdroms on newer macs


it seems that i can t boot to an older cdrom disk on my new powermac g4. i think it s a digital audio model. is it because the newer machines won t load older OSes? one of the disks i can no longer boot includes my 9.1 disk which came with my retail version of OSX. this is problematic. the install disks that came with the machine boot just fine. can anyone make any suggestions?

I'm having a similar problem with a new G4 1Ghz. I can't boot my RsyncX CD anymore. It shows up under Startup Items in OSX (10.2.4 and 10.2.5), and I can select it, but it just defaults back to booting off the hard drive. If I hold down option at startup it shows the hard disk but does not even show the CD. I've tried updating the firmware to current versions, and operating system but so far no luck. Anyone got any ideas? I'm getting quite desperate as I can't get our standard lab build to install from the servers anymore without our build CD.
I think the problem may be that you can't just not boot OS9 any more, but you can't also boot anything prior to 10.2. The RsyncXCD is based around 10.0 - hence it shows up in startup items but cannot be booted from. I'm trying to make a new CD image based around 10.2, but its damned difficult to fit on a CD. Great thanks Apple - so much for backwards compatability!!!