If you set the drive up using OS X Extended then the PC won’t even recognize it. What if you need to use the same external hard drives with both types of computers? If you set the external drive up using NTFS then the Mac can’t write files onto it.
How to format an external drive (Windows): NTFS is the standard for Windows users and OS X Extended (Journaled) is the standard for Mac folks. Most photographers will want to format their new external hard drives using their operating system’s optimal style. It is essential that you do this right away, before you start using the drive, because the formatting process erases everything on the external disk. Format and partition your new disk immediately, before you start using it for backup or for additional file storage. Regardless of brand or model, the very first thing that you must do when you buy a brand new external hard drive is to format it properly for your system. Likewise, the Mac OS X Operating System can read from, but cannot write to, an external drive that has been formatted for a PC using the NTFS file system without additional software. To this day, a PC cannot read from a hard drive that has been formatted for the Mac without additional software. External hard drives are great, but they must be formatted properly before you start filling them up with important information. I use external hard drives to store all of my photos and for my backups.
