What a bummer.

I'm also rather lax about backing up. To offset this I use 2 hard drives in RAID 1 configuration in which data is written to 2 drives simultaneously.
This is good protection against hard drive failure as it is very unlikely for both to fail at the same time.

Of course it doesn't protect against a nasty virus - nor against lightening strikes!

Here's a wiki link should you wish to read more: http://en.wikipedia.org/wiki/RAID

Mike.