Startup disk drives for G5?

A new drive in a G5 isn't working as a Startup Drive.

I just installed, into a friend's G5, a 1TB Western Digital Green WD Desk Top Hard Drive 7200 rpm SATA 6 GB/s,

then partitioned it into 200 GB and 730 GB partitions, both Mac Extended (Journaled),

then installed from the retail DVD MacOS 10.5 (Leopard) onto the 200 GB partition --

all seemed to go well...except that the G5 won't boot from the new drive.

System Preferences -> Startup Disk shows the new drive, and I can select it,

but on restart, the computer starts up from the old (10.4, Tiger) disk.

Restart with Option shows only the old (10.4, Tiger) disk.

Any ideas?

Could it be that the WD SATA disk I bought isn't bootable in a G5?

Is there any way to ensure that the next disk I buy is bootable in a G5?

--Gil