I finally got my act together and bought myself a Synology DS211j NASÂ with two 2TB drives. I'll use it as a shared network disk at home and I intend to backup to it - as I also have a home office it'll feel better to be able to also backup company related data somewhat more safely. My previous backup was only copying data from one HDD to another within the same physical machine.
To make it slightly more resistant to disk and hardware errors I've configured the disks to do RAID1 (all data is stored on both disks simultaneously).
The GPLv2 license was provided printed on paper in the package.