I did think this Which? article advising people to smash up old hard drives was a little extreme, ill advised and wasteful. It was of course widely reported but few people did much other than repeat what Which? said rather than offer a more informative opinion. Which is basically what reporters seem to do nowadays, copy information from some other place without actually doing any research.
The Register has a better take on the topic. Personally I use a program called Eraser but a Wikipedia page on the subject list many others. Destroy the drive if you are really worried but for most people, proper erasing should work fine.