Hello Henrik, I'm not sure about MacOS restrictions but I have a 20 Gb drive in my PB 3400, most of it initialized as ext2. I have several few Gb MacOS partitions but its been a while since I've booted it in MacOS. From http://store.powerbook1.com/harddrives.html#ide (where I got my drive), it looks like you can go up to 60 Gb. Cheers, Andy Ptak