Macs can read/write to FAT32-formatted drives, but can only read NTFS-formatted drives. You cannot format a drive with data on it without wiping the data. If you plan on using a drive that both Macs and PC's need to read/write to, you'll need to format a drive using FAT32. Your best bet would be to then copy all the files over to your newly formatted drive, and not plug an NTFS formatted drive into the AEBS. As far as hubs go, any powered USB 2.0-compliant hub should do. I use a few them made by Belkin.