Open season on hard disks?

In the last month hard disks in three of the machines I use regularly have had hard disk failures — the SRCF, my lab machine and now my laptop. Whilst worrying from a data integrity point of view, it is interesting that all three machines are approximately 2.5 years old, and running pretty much 24 hours a day (even my laptop generally gets left on over night). An indication that hard drives with three year warranties are an excellent investment perhaps? It has also been a well-timed reminder of the importance of backups!