Hard Disk Drive (HDD) larger than 128GB
The ATA-4 controller working in the iBook Clamshell is not able to take advantage of drives larger than 128GB. Apple states that -as a guideline- all Macs released after June 2002 can address larger hard disks.
If a 160GB hard drive is installed, the Clamshell will only recognize it as a 128GB HDD. If you want to use the full capacity, only a workaround helps.
Place the hard drive in an external enclosure, connect it to a newer Mac and partition it via disc utility. Your partitions can be 127.99 GB max. The second partition of a so-called 160GB hard disk (you will never get what you see) would add up to 21 GB.
Then put the drive in your Clamshell and install your favorite operating system (Jaguar, Panther or Tiger) The Speed Tools ATA Hi-Capacity Driver for $24.95 USD is a DMG and the second partition will be accessible in a minute. The drawback: There are some limitations in using OS9 (only Classic mode possible) and hard disk tools.
credit: http://www.ibook-clamshell.de/content/view/174/1/lang,en/