No RAID? I hope you have another device to back up your backups.
If you have a spare PC chassis that will hold at least three drives and a motherboard with enough connections, you could do an LVM RAID (level 1, 2 mirrored and one boot disk) and run a headless linux install as a middleware backup platform. Mount the RAIDed volume as an NFS share and file backups become as easy as a shell script and a cron job (or more complicated if you want incremental backups with rsync or something similar). You could then offload the middleware backups to your new goflex disk for double (if not purely redundant) backups.
I'm just extra paranoid about data loss these days.
edit: I did not intend to have a smiley above my post. This is serious business.