My much loved mirror door drive powerpc G4 died last night (power supply kaput) and I pulled the three IDE drives it contained this morning and put them in new external IDE to USB enclosures. With two of them (Western Digital caviar 160GB and Western Digital caviar 250GB) I get the "The disk you inserted is not readable by this computer" message on my intel MBP booted in OS10.6 or 10.8, my intel Mac mini running 10.6 and an old G4 mini running 10.4. They show up in Disk Utility but the verify and repair options are greyed out.
The third drive is an IBM Deskstar 80GB that shipped with the G4 and was the boot drive (OS 10.5). It spins up but does not evoke a "not readable" message or show up at all in Disk Utility.
All three drives were working fine last night before the MDD G4 died.
Any help getting these drives working as external drives would be much appreciated.

I'm assuming you had no back ups?

Check the jumpers. They should all be set to master.

and remember, you cannot boot off the drives until they are reformatted for Intel machines.

Who was that masked man.

What the frick! Talk about a hit-n- run....

Everything except maybe what I was working on the last few hours is backed up. No disaster there.

I was just hoping to pop the drives into external enclosures, plug them into one of my other machines and be off and running.

The Deskstar came out of the G4 with jumpers set to cable select. The WDs have no jumpers at all.

Well that certainly is a relief. BTW.. welcome to our little corner of the Mac world.

Don't need to boot off the drives. Just want to continue using them. It would be nice to to so without formatting and wiping data