I believe the 400 has a 4 x 4 embroidery area. You can download designs within this size at SHOP or at DOWNLOAD DESIGNS. Those at SHOP will offer different formats and sizes. Those at DD are usually within the 4 x 4 and are PES. Since the DD are free they are not available in a variety of formats or sizes.
Regarding DOWNLOAD DESIGNS, they are free to all who are members of Ann's Club. Those who are not members of Ann's Club are limited to only designs with the download icon. This will be explained and the icon presented on the second screen at DD.
You can be come a member of Ann's Club here - http://www.annthegran.com/AnnsClub.aspx The fees are at the bottom of the screen.