At the risk of tooting my business' horn, my "Constant Care" program has saved two PCs' data in the last two weeks. Both were coming up with "bad block" hard drive errors so I alerted each owner to the messages and advised them to back up their data right away. ONE HARD DRIVE DIED TWO DAYS LATER.
Constant Care comes out to the cost of two basic PC tuneups a year and keeps you secure and updated as well as keeping an eye on things like the above.