The 5 year warranty is something to take seriously, but it's also true if a HDD is to fail on you, it'll do so within a short period of time, and if it is to last a year it's likely to last several more. Given that the Seagate costs less and is slightly faster (single 1000GB platter versus two 500GB platters), you can't go wrong with either. If you're not bothered by the cost and just want peace of mind, go with Caviar Black; if you are bothered by the cost and believe the HDD will last long anyway, go with Seagate.