[iMac] cannot boot new 500 GB SATA II HD installed into G5 20" iMac

[Steve Goldstein]

Folks,

Any insight would be helpful.  My wife's G5 iMac came with a 150 GB 
HD (Western Digital).  She has outgrown it.  So, I ordered a 500 GB 
Samsung SATA II HD501LJ.  I cloned the existing HD to it using Carbon 
Copy Cloner.  The 500 GB Samsung was in an external USB 2.0 SATA 
enclosure.  After cloning, I installed it inside the iMac, and it 
would not start up.  I can start the iMac with a backup external 
Firewire drive, and when I do, I can open the 500 GB Samsung 
internal.  Everything seems to be there.  I also rebuilt its 
directory with DiskWarrior, repaired permissions, and Zapped the PRAM 
through three bongs on a startup.  Also pressed the PMU button inside 
the imac.  Nothing works.  Booting with Option key held down or 
selecting StartupDisk in System Preferences shows this new Samsung 
drive as a valid startup drive.  If I try to start up with it, I get 
the gray screen with the Apple logo and the rotating wheel/gear, but 
that can go on forever and ever.  Also, I tried a Safe Boot, and the 
same thing happened: the gear wheel kept spinning.

AppleCare was no help.  I got a clueless guy with an Indian accent 
who put me on hold for about five minutes while he consulted "a 
supervisor."  Then he came back and told me to bring it to Apple 
Service.  Grrrr.

Does anybody know if the G5 iMac can boot from a 500 GB [Samsung] 
SATA II drive?

BTW, I have a 20" Intel Core Duo iMac, and I only regret that I 
cannot take that one apart (at least without voiding Cupertino's 
protective cloak).

Thanks for any input.

--Steve (who has been taking Macs apart since 1989)