Do you have your work backed up.
At the end of each week I copy my work onto 3 memory sticks.
At the end of each month I burn my work onto a Cd.
At about every six months, I register my latest updates with the UK Copyright Service and the US Copyright Office.
Your work is copyright by simple virtue of you having written it. Like Khai, I write in Scrivener and back up to Dropbox and to the default back-up. I also back-up to a stick once in a while.
Emailing establishes an extra time-line to prove that it is your work - you couldn't have mailed it anywhere if it hadn't been written on that date. It's the equivalent of sending yourself a copy of the mss in the post and not opening it.
My work automatically writes to a memory stick and external hard drive at the end of each day. And like Khai, I email my work to myself periodically. I find that's enough, and so far (touch wood!) have had no problems!
Adrian, to be honest, I think you're overdoing it, even if only in terms of the time it takes for you to do these tasks. There is so much advice being peddled to writers about backing up in every single way possible that it comes across as a little hysterical to those who have actually lost and recovered their files after some system crash or hack.
In my case, I write at home and at the office and send my daily snippets of prose back and forth between my personal and work email addresses (and respective folders on each computer). This means that I essentially have an email and file backup of every change to my work-in-progress in two separate locations. At home I write in Scrivener and back up everything in Dropbox and the default Scrivener backup folder.
When my Mac randomly crashed about a month ago during a system update, I was left with no choice but to have an Apple "genius" wipe my entire HDD. When I reinstalled Scrivener, I simply uploaded my Dropbox files and was back on my feet.
In terms of copyright, my work is protected under Australian copyright law the instant it is written. For this reason, in Australia at least, some literary agents have said that writers make themselves look paranoid when they submit proposals with the copyright logo on every single page. I'm not sure what it is like in the U.K. though.