Unless you want to edit them, you don't NEED to open them on your computer. Instead, you can just copy them onto whatever media it is that your embroidery machine reads. In my case, that's simply a USB thumb drive. Then I insert that into the computer and open them from there. It is handy to have a "viewer" so that even if you don't wan to edit them, you can view them in the file folders on your computer, but it's not necessary.