On Thu, 3 Mar 2011 21:13:21 -0800 (PST), Shaun Eli
wrote:

CDs and DVDs are almost free. You'd need two USB hard drives to have a
continuous backup off-site.

I mostly work on the same files so incremental backup on a weekly
basis is quick and easy. Though I have thought of getting a second
external hard drive and just swapping them back and forth as backups.

So they're twice nothing. So what? CDs are too unreliable.