I confess I've had a real hassle getting some USB drives formatted back to Apple Partition Format after they've been used on a Windows system and partitioned with fdisk. Disk Utility would hang, diskutil would hang, and pdisk would report success at manually editing the partition table to APF but I could never actually create HFS partitions with it or Disk Utility.

Sadly enough, I hooked up the drives to my windows system and Macdrive partitioned and formatted the drives as APF/HFS+ perfectly in 15 seconds.

I should note that these exact drives in these enclosures were initially used on this same G5 system formatted as HFS+ for the first year i had them, then used on a Windows system as NTFS for a year, so it isn't a matter of the USB enclosure not working on the Mac. They've been scanned from front to back with Diskwarrior, Drive Genius, etc and several terabytes have gone back and forth on them with no errors.