[bluenose69]

Advice: switch to latex with beamer.

Latex has a fairly long life time. A friend found the 20-year old source for his thesis and thought it would be fun to see if it would still compile in latex. Sure enough, it did, after just a few header lines being changed (sometimes library names change).

[emacdona]

And, even if it didn't compile (which is a big "if"), you'd still have a postscript or pdf file of the presentation. I have yet to find a non-DRM'ed pdf old enough to cause me trouble when trying to view it.