While not helpful for your neighbor, I always insist on setting up a Time Machine disk for every Mac I ever help set up. My wife's parents had a ten year old iMac, for example, which crapped out a few months ago. Wouldn't boot. We concluded that it was time for a new one. The new one happily restored itself from the Time Machine disk and they didn't lose anything.

Time Machine is probably the best thing Apple's ever done for its users. Now, if only they'd bring back ZFS...