I back-up to an external hard-drive. I started out just using
synchtoy to copy the document directories, but then I decided that wasn't good enough and I moved to using Vista's built-in backup software and scheduled it to run weekly (low rate of change on my home PC). The backup software will (supposedly) backup email, etc as well as user-files.
As I type this I have realised that I've never tested the restore of the backups ... I'll have to do so after the next on on Sunday evening ...
Herbie