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I don't know how complicated your presentation is, but you could convert it to PDF

That won't help if you have transitions and effects though
 
isn't there a way to export from keynote to PPT?

if not, convert the quicktime file to something more friendly in the windows environment, mp4 or something?
 
Is your Mac a laptop? or can you borrow a friend's Mac laptop and connect it instead of the school's PC?
 
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