If you have the latest firmware the 8GB limit does not exist. I installed 10.4 to a 20GB hdd in a firewire enclosure then transplanted it into my first generation clamshell which boots 10.4 fine and uses all 18.7GB of the hard drive. (A 20GB drive only has 18.7GB) To install the firmware you must have macos9 installed on the hard drive, it will not work from a CD. I think I actually updated mine booted from a USB flash drive, but that's not supposed to work, so your millage may vary.