Hi, I have a portable USB disk that will be used with 3 machines, one each of Mac (10.5), linux (CentOS), and windows (XP). In particular, it is absolutely essential that on the mac and the linux box the files be shareable without read/write/permissions problems. Is the answer to have 2 partitions, one HFS+ (non-journaled?) and one FAT32? What about GPT vs Master Boot Record? Any other thing to watch out for in the set up? Thanks. All information appreciated.