I'm just getting into the market of "digital signage" so there are a lot of
media players that for the most part are built on Windows Embedded and have
proprietary playback of image files as you point out.
In large part, its PowerPoint that is being used to create the content for
many applications but the paint programs can be used to create large format
like 30" x 42" files noting I'm referring to what CAD markets call D size
format for convenience. As you've likely observed there are many sized of
LCD screens and TVs being used as display platforms.
The animation PowerPoint supports would be nice to reuse but that requires
Microsoft supporting a light-weight player that is programmable --or--
releasing its player as open-source so developers can reuse it in these
emerging markets which is where many of the new jobs are being created.
Don't slap me for saying so but I'm compelled to look at what the OpenOffice
has to offer in this context. AFIC the more Microsoft drags its feet the
more I and others are compelled to abandon their platform and its software
products as they continue to make it impossible to achieve contemporary
goals.
Meanwhile, I hope to continue to learn PowerPoint never having thought
before I would actually need or want to become a SlideMaster

so thanks
for your interest Bill...