Now back at home, uploaded all my pictures (7000 or so for a 3 week trip) to a PC and burned some DVD's to send to relatives. (If I used CD's, would have taken three of them to hold one 2 GB memory card's contents) At least one DVD had an error on it. Heaven forbid, if I had only one copy of each picture to bring home (for example set aside the memory cards and did nothing else, or relied on CD's or DVD's made at Walmart or Walgreens or wherever to hold my pictures while I re-used the memory cards) ...

Are CD's and DVD's actually less reliable than HDD's and memory cards? All the descriptions of CD's etc. mention that the reading process is never error free and error correction techniques are used. A scratch or a speck of dust in the wrong place could make a particular data read too far off base for the error correction process to handle. For movies and TV shows, the error will just show up as a momentary off color dot or streak but for data, the results of the error could be disastrous.