Trouble Going From 10.4.11 to 10.5.6

I have a PPC G5 desktop - running 10.4.11

I have the OS-X Install disk for 10.5.6

Quite all applications

Used Disc Utility to Repair all permissions

Ran the Installer for 10.5.6...

First time I got an error that said "can not verify essentials"

It suggested that I quite and try installing again.

I did - second time the installer just hung up - and timed out.

Then I tried to reboot the existing system on the hard drive - and the system won't boot from there. Just goes into the "looking" mode.. with the little rotating circle..

Booted from an external hard drive {a CCC Backup} - and looked at the System Folder/Library on the internal hard drive - lots of New Items there - I suppose from the attempted install of 10.5.6...

Copied the System from the external hard dive back to the internal hard drive. Deleting everything that wasn't on the external drive from the internal drive. So the two Systems are the same..

Restarted - selected the internal hard drive as the start up disc - - The System will still not boot from the internal hard drive...

What do I need to do to first fix the internal hard drive System so it will boot ...

and second

What needs to be fixed in "essentials" {whatever they are} so 10.5.6 can be installed

Hope that is not too confusing..

Carl Beck