I really don't know why it's taken so long. My friends in the various discussion forums that I've contributed to over the years are accustomed to me berating them for not doing it and I know from bitter experience that it's better not to get caught with one's pants down: so I'm embarrassed to admit that recently I haven't been making regular system and file backups!
The reason for my slovenly behaviour? I couldn't figure out how to get Simple Backup to write the backup to a remote network drive!
My early attempts to implement a backup strategy were thwarted by my difficulties with Samba and recently my attention has been monopolized by upgrades and laptops. However, today I set myself the goal of getting my backup strategy back on track. As always, it took an awfully long time to realize that it shouldn't have taken such an awfully long time.
Having fixed Samba (not that it was really broken!), I thought that pointing Simple Backup to my chosen destination directory and telling it how often to backup my files was all that was required. However, every time that I pointed to an existing directory on the network drive, Simple Backup demanded my login and password: that's not ideal if you want to automate a backup process. I tried mounting the drive without success and even looked at alternative solutions; including using rsync via the terminal.
Ultimately, it proved easier to start from scratch and, using Windows Explorer (on a Vista machine), I created a new CIFS share on my network drive called (in my case) UBUNTUBACKUP. In this share, I added two additional directories, one each for my laptop and desktop.
I had to set some pretty liberal read/write permissions, but the vanilla directory did the trick.
It's worth noting that, despite the inference to the contrary on the Simple Backup Help Page you don't have to use a secure shell (ssh) or file transfer protocol (ftp): Samba (smb) works just fine!
Moreover, you don't have to use the ip address of the remote machine: NetBIOS names also work.
After assigning the destination addresses in both Ubuntu machines, I rebooted to test whether the login/password issue would return: it didn't and subsequent test backups showed that I had finally managed to achieve the simplest of tasks! It seems that the point that I'd missed is that writing files to another machine on your network requires the destination directory to be a shared directory with permissions that are liberal enough to allow access for a remote source.
Now that it's working, all I need to do is to figure out what is worth saving and how often!