If the drive is formatted HFS+ (which is the default format for an iPod on OS X), you aren't going to be able to read it without a 3rd party app like MacDrive. I was able to take my iPod from my Gateway to my iBook without problems, and copy files back and forth (onto/off the iPod), but that was because the drive was FAT32 formatted. It was pretty cool; I'd expected iTunes to try to format my drive upon connection, but instead, everything showed up. So yeah--if you want to use an iPod on both computer types, it needs to be FAT32 formatted.