Tina blake; as far as I know Viking is the only one who makes embroidery software for the MAC and that was as of this past yr. Its the 5D for Mac. I'm not sure on formatting the USB; in my Viking machine I can use any usb. I actually store the one that came with the machine so that if I ever trade it in I'll have it. I also want to add, there is a way to partition you mac to also operate a windows software and if you take it to an Apple store they'll do it for you. Also ask them about the formatting of usb for their machines. You can find software in all price ranges, even free ones they all have different features that make them unique. I have the Viking 5D Professional Plus and love it, its the same that Pfaff uses and it recognizes just about all formats. Floriani has a good software package and I know they work with Brother too. If you do a free software search on google you should be able to find others. Good luck.