Slightly related to the subject of reading CD's in 100 years:
On one of their recent space probes, NASA put a DVD (just the disk, in a
little pocket on the outside of the probe, possibly with a plaque of some
kind but probably no directions on reading).
I suspect DVD's are much more complex than CD's. I would trust a CD on a
space probe more than I would trust a DVD. The records on Voyager (both
Voyagers, I guess) -- which include styli and playing directions -- strike
me as a MUCH better idea.
-- Derek