An "extra" external Hard Drive is probably about as "permanent" as anything else, if you check occasionally for signs of failure. The problem is that to benefit from it, you have to put everything that needs backup on it.

If you observe reasonably good storage practices, CDs probably are "permanent" for the time frame most would be realistically concerned with. With special care, and perhaps a little better burners than are in typical desktops, they are probably "archival." With some fairly common labelling and storage practices, they may not last too long.

I'm not (yet) impressed with the reliability of DVDs for storage, but they should improve fairly rapidly as more people use them.

If you do backup with CDs or DVDs, you should be aware that the file naming conventions there are significantly different than for Hard Drives. If the burner changes a filename it can make the file unusuable, even if it's recoverable. This happens often with "html page files" where you have a document, and a folder with the same name for all the "includes." Since the original folder name is used inside the document to "call" the inserts, changing the name(s) makes the document fail. You have to open the document in a browser, and "save as" to a CD/DVD compliant name before you start the burn setup.

Agreed: a can of wigglys.

John