I've been doing some last stage testing of a new 3rd party add-on for Movie Maker... for MM2.1 in XP and MM6 in Vista. It'll be released soon, but being under NDA (non-disclosure agreement) with the developer, I can't yet say who it's coming from or what it's called.
What I can do is use my copy to show the kinds of things you can do with it. My samples are at this vimeo channel...
http://www.vimeo.com/PapaJohnTestClips
The info under each explains it.
The tool lets users of Movie Maker take extremely high quality still pix and do the kinds of pans and zooms that is done in Photo Story 3 and other slide-show type software... but does it even better... larger pictures like my panoramic sample that is a JPG of 14,525 x 2,476 pixels.... more than twice the width of the 7,200 pixel limit of Photo Story 3... and with non-linear movements in addition to the usual linear ones.