I recently installed the latest version of ubuntu via a live cd on my 2.4 GHz unibody MBP. I don't know why you can't boot from the cd. My only suggestion would be to try burning another disc.
Both 32 and 64 bit versions of the ubuntu 8.10 live cds and alternate cds boot fine on my 2.4 unibody MBP. No reason it shouldn't work on yours. Maybe the disk is faulty.