However my words are coming across in this discussion, I'm really not a very trusting guy! Many of my early computer experiences were in the early '80s with surplus hardware from the '70s, including a PDP-11/45 that was a bit beyond the 300th DEC manufactured. Of course everyone used magtape back then for backups, and those were quite reliable (originally intended to be reliable off-line storage).
ADDED: and there are other precautions to take. E.g. I only bought my optical media in April and October, to minimize the environmental stress during shipping.
In the digital preservation community, the standard is at least MD-5 / SHA-1 and most people are moving to SHA-256/512. With a CRC-32 check you're likely to get false-negatives for modern data volumes and there are disturbing reports of CRC failures at higher than expected rates[1] which suggest that the best answer is using multiple, cryptographic hashes particularly since the computation has effectively been free for a least a decade except on unusually CPU-starved storage hosts.
1. I don't recall the paper but I believe it was a followup to http://conferences.sigcomm.org/sigcomm/2000/conf/paper/sigco...
The experienced storage admins I know share that hope but don't trust vendors not to get it wrong. It's just too easy to miss a factor which turns out to matter.
> I was merely responding to the assertion that CD-Rs are entirely unsuited for archival purposes, and backed it up with my own experiences over a decade and a half.
Question: have you done bit-level checksum validation on that old media or is that just the ability to read without errors? There's a little bit of error correction built into the format but I wouldn't trust it for anything important.