IME, if a drive is going to fail, it's going to fail in the first hundred hours or so of use. In my entire life (of using hundreds of disks), I've only had three failures. Two of those were on the same server, at the same time, in the same RAID array and took out the whole array -- the data was gone forever. Thank the gods for backups.

So, just make sure you take backups pretty regularly because you never know.