yeah, i've heard of data loss on some older cd-roms. duplicates are a good idea, also using a good quality brand, should help. a while back, verbatim made "archival quality" that they guaranteed would not degrade for about 100 years. now they've dropped the "archival" from their name, but i've still never had an issue.

you could also rotate disks. once you've got one that's two or three years old, copy it back to your hard drive and then burn it to a new disk. at least until something better comes along.

and no, i don't think dvd-rom is the answer. cd-rom has a more standard format, and if you accidentally ruin one or it 'goes bad', you only lose 700mb of data, not up to 4.5Gb or so.

also, as flash drives become cheaper, you may be tempted to backup to flash memory. i'd really advise agains that. why? leave one next to a good sized speaker and you'll see.