swapping Powerbook hard drives 17" to 12"

I have 2 Powerbooks, 17" & 12"..

17" is OS 10.4, HD=60GB / 12" is OS 10.5, HD=80GB

The logic board on the 17" is no good. It will not boot up all the way... So then I booted it up the 17" in Target mode and the hard drive and all of its contents shows up as an external hard drive on the good 12". But 1 minute later it freezes and nothing on the screen moves..

Now for the 12" Powerbook : After trying many times. I took out that hard drive from the 12" and put in the 17's hard drive into it's place.

Everything clicks in fine, every screw goes back in place fine (I don't have a problem with dissembling and assembling the casing and following the detailed instructions).

But when i boot up the 12" now, it shows the APPLE icon, then goes blue screen.

What do i need to do now? The hard drives were compatible correct?

Do i need to boot from the install disk & run something first for it to read normally? What are the steps i need to do to run the hard drive. I heard no clicking noise from the hard drive - the spin sounds seem normal. So it all seems in check. But the screen remains blue, and the arrow-cursor is also there able to move using the track pad.

The reason why I do this hard drive swapping is so i can get my 17's work files transfered onto an external drive.

Thanks for the help..

The drive from your 17" does not have the drivers required to boot on the 12".

Am not familiar with the PowerBooks. My first Mac was an Intel. I'd go back to connecting via target mode with your 2nd external connected simultaneously if you have enough ports on the 12" for a direct copy from the 17" to the external.

If not, you'll have to copy to your internal, disconnect, attach your external then copy to it. Yeah I know, pitr.