Hi, I need some information regarding which file systems (for an external HD) are compatible with OSX. These are my questions: 1. Which file systems are compatible with OSX on my MBA? By compatible I mean the ability to read & write. (I know that NTFS is incompatible and FAT32 is compatible - but are there some other file systems I'm missing?) 2. Which file systems are compatible with my Airport Extreme router? 3. Which file systems are compatible with OSX, Airport Extreme AND Windows? 4. Is there any reliable software that can convert from NTFS to another file system without formatting the hard drive? Thank you very much for your time!