Just to note about MintPPC... I tried it on a 500mhz Pismo, which pretty much has similar specs to the 500mhz iBook (same graphics card, etc). I was not satisfied at all. X didn't work to initially, a known problem, so I had to find a xorg.conf file on the MintPPC forums for the Pismo that would make it work... but said file also disabled all the hardware acceleration so everything video related was painfully slow. Do they really call that a "fix"? It was completely unusable. Since the iBook seems to have the same graphics, I am going to guess this would be an issue on it as well, unless someone here knows a proper fix that will get things working smoothly.

I also didn't like that all the GUI elements in MintPPC are green and it seems impossible to change them completely.