I'd say you need an HD projector and some kind of media player to connect to it with the files on it. The projector can either be 720p or 1080i/p. Both of those types of projectors will give you a better resolution than a DVD playing on a standard definition projector.
To prepare the files you will need to bring them into photoshop, set the size to work with 720p (1280x720) or 1080 (1920x1080). Some projectors have different sizes that are outside of these standards too, so you'll need to make sure you check the projector first. You're best approach is probably to just make them for 1080 and then allow the media player to scale the file down for 720.
You then will need to import them into a compositing or editing application like After Effects, Final Cut, or iMovie and create a sequence with all of your still set to play for certain amount of time. Then you will export the sequence as a movie file of some kind (ex. .mov). The resulting file can then be played from a device connected to the projector. You can see my post in the Film/Video group here
to learn about using a WD Media Player for HD video.
I hope this answered your question. Let me know if you have anymore questions. Working with projectors and HD can seem like a large task but there is lots of info out there online to help you through the process, even tutorials on how to use the software.