Dual Formatting of External Hard Drives (PC and MAC)

You can do that?? It turns out, yes.

Plug the drive into a USB port on the mac. Go into Disk Utility (You can find the utility fastest by clicking on the "magnifying glass" shaped icon on the far upper right corner of the screen, which is called Spotlight, and typing Disk Utility.

Then partition the drive, selecting the option to create 2 partitions. This will format the external drive. Select mac formatting for one and MS-DOS FAT for the other. The trick is go go into "Options" after you enter the Partitions tabs and under options select the bottom of the three options, which allows you to create a root directory that will allow the MS-DOS partition. Otherwise, it isn't even an option.

After being done formatting, you will see both partitions on the mac with their assigned names, and if you plug into a PC you will only see the PC partition with its name and letter, like E: as assigned by the PC.