yeah - HFS+ will not work on 8.0 or before, they require HFS. From 8.1 to 9.22, HFS+ is needed if you are using a Hard drive larger than 2GB.

NJRoadFan is right, Apple's IDE implementation is really brain dead and this affects machines up to the G4 Laptops (up to the G3 Blue&White Tower with desktops).