None of the above,
some HDD manufacturers have utilities which you can use to assess whether the thing is packing up or not - IBM certainly did. In addition, if you notice the clicking and you have time on your hands, put the tip of a long screwdriver against the side of the drive and put the handle to your ear to determine the origin of the noise.
I've just backed up the entire hard drive on both DVD and an external HDD.
Would it that everyone were so wise.
BOFH