Wiki'd dd and honestly it's a bit over my head. I'll have a bit more of a read, and see how to backup to an external HD.
I've mainly just been enjoying using a 10yo laptop (that I liked) with few issues. Only issues have been; handling multiple Gnumeric files (which I think is reasonable given the age), hdmi sound (which I had a crack at fixing, but gave up as the solutions didn't work) and the strobe-effect on AbiWord (which I couldn't find a definitive solution for, so just use leafPad 90% of the time).
The whole experience sort of makes me want to try and look for an old cheap laptop that's close in size to the macbook air, with enough battery to watch 2 films.