Photos are generally 4:3, just like standard video.
You don't really want to chop the tops off all your photos so that they fit into a 16:9 video, do you? Especially when it's not necessary in order for the photos to display in either a 4:3 or 16:9 project.
However, you can use Photoshop Elements to crop your photos to any shape you want. As I show you in my books, you can even pre-set the Crop Tool to cut your photos down to 855x480 pixels at 72 ppi, the size and shape of a 16:9 video frame.
Along with Steve's tips, this ARTICLE will step you through automating the Scaling of stills. I start out with info on how to do it in PS, and near the bottom, Neale adds the steps for PSElements (thanks Neale).