Above are all correct. A computer cannot open a file to allow viewing the image of a design..you need a special software to read the data that accompanies the design. You need a viewer to see your design as an image (like a picture). I have been in love with Embrilliance Thumbnailer for several years: I unzip a folder and my format (pes--that's the format I have it set for) design is easy to select..then I send it to my embroidery folder where all my designs are displayed as images. Makes it so easy to select what I want to stitch out. There are many viewers....some are programs that have to be opened and you work within--My Editor & Pulse Ambassador are a couple that are free. I love both for editing , reformatting, other needs. SewIconz is another like Thumbnailer--I think it costs about $25?, Thumbnailer was $40 when I bought, but has been worth every penny as you own (CD w/serial #) and can install in another computer. I started with XP and now up to Win7 Ultimate & Professional. There is another freeware viewer I started with back in my embroidery elementary yrs--it is called ''pesview", but I don't know what format you use. I'd be happy to share the link for it.