External DVD Burner

I have a casing that I put my DVD Burner in. It just hooks up via USB. At this point I believe that the Combo drive in my iBook is busted, but I am torn between buying Mac OSX Tiger and iLife, or a new combo drive. If I boot into Linux, it recognizes the drive fine. But is there a way I can get my iBook to recognize outside of Linux, so I can put the Mac OS cd in and boot from it inside the external drive? Or does the iBook only recognize it in the OS?

EDIT: I read the help and went to the startup disk selecter, and all that shows up is my hard drive.

I don't think you can use a usb drive to load the system. If I remember correctly you will need a firewire drive to load your OS.

as far as i know.. you can only boot from the internal drive.
that's why apple has the cd roms for tiger. they have the media exchange program