For some time my computer made clicking sounds and other—surprisingly loud—noises: signs of immanent hard drive failure.
I didn't act on it for far too long. Even with an excellent backup system in place, that feels like living on the edge. Yesterday I installed a new hard drive. Since I don't want to spend the money for a decent SSD, and the new hybrid drives don't work with disk encryption, I bought a regular 7200 RPM laptop hard disk.
The speed improvement is noticeable compared to my old 5400 RPM one.