Re: CD Life Expectancy
One often overlooked aspect of long term archiving is whether the hardware necessary to read the media will be available in the distant future - consider the many tape backup types which are dead and gone! In many cases CD backup has been replaced by DVD ( more than one type -+R, +RW, -R, -RW, DVD-RAM) which is about to be superceded by Hi-density - so far 2 different standards fighting it out. Who has 8track audio tapes or even tapes as opposed to CDs for their audio, let alone Betamax or V2000 for video tapes!
MikeD