On my iMac (G4 1GHz, 1Gb Leo 10.5.7)  I want to use a Linux version... 

Therefor I downloaded Ubuntu 8 (and 9 and 7). By Disk Utility I made a bootable partition on an external FireWire drive... Changed my startup disk to this partition, and rebooted...

Did not work... although the startup disk appears... (By holding down Alt-key during rebooting)

Diggin' around on the 'net, learned me in a some way I needed a boot-program, this is the reason why I'm writing this e-mail... 

And now the question: is there an unambiguous manual for this newbie that will guide me through this?

thanks in advance, 

Hubert