I'm curious .... how do you maintain your elibrary and back it up / copy it?
After downloading my ebooks I then add them to Calibre, and change the format to EPUB where necessary. I gather metadata if needed, and add tags etc.
Every now and again I highlight all books in the library and choose the Save to Disk option - and copy all the books onto a 16GB usb stick.
That way, not only have I got a copy of all my ebooks (and metadata), I can download to any other computer should I lose the hard drive on the lap top they currently sit on (which has happened to me before).
But how does everyone else do it?