a.. Where images are saved
b.. How they're named
c.. What range of slides to export
d.. What resolution to export them to
and
Improve PowerPoint's GIF, BMP, PNG, JPG export resolution http://www.pptfaq.com/FAQ00052.htm
I realize that wide-screen display isn't your issue, but the problem's similar
... getting PPT to change the slide size w/o distorting the contents of the
slides. Scroll to the bottom of the page and you'll find some code that'll get
you where I expect you need to be.