Firewire drive doesn't function as a boot drive

[Platform]

I have an iMac G5 (iSight) running 10.4.11....

Just got a firewire drive so I could use it to boot off. (My Book 500GB Premium ) Connected via Firewire (400) formatted Mac OS X Extended Journaled and partitioning system "Apple partition map"

However the drive does not show up in system preferences as a bootable drive nor does it show up when booting and holding the option key...

So any suggestions?

Thanks

 

[mad jew]

Did you use the discs that came with your machine to install the OS?