I've been using ActiveSmart to monitor my hard-drives health for a few weeks now, and its telling me my brand new 1.5 TB hard-drive is half-dead already. About on-par with one of my hard-drives which I know is at least half dead because I've been having some read errors and heard ticking noises. Now I haven't actually noticed any problems with my 1.5 TB drive; should I be concerned that it's going to crap out on me too? Or could ActiveSmart be giving a mis-diagnosis because I use it a lot or something (I've used up 795 GB in the 2 and a half weeks I've had it). The events that ActiveSmart has been catching is "Hardware ECC recovered". Maybe these new fangled super big hard-drives somehow rely on ECCs to squeeze out the extra space, but this isn't actually a cause for concern?
Modern hard drives have massive levels of ECC. This allows them to handle the massive amount of noise in the read heads. The 40 byte ECC from a 2004 vintage drive can recover from a 50 consecutive bit error. The size of the ECC block is steadily increasing with drive density so modern drives have even bigger ones (because the higher densities have a higher error probability).
As a side note, of the half dozen HD's I've seen fail only 1 ever generated SMART errors before bricking itself, and it didn't start until suffering drop damage sufficient to render the OS unbootable. I wouldn't put much faith in it's ability to detect problems in advance.
The high density of bits on that drive will lead to more reading errors which are corrected by the drive's firmware. I don't think it's a huge concern. Wikipedia doesn't list the value as critical either (source: http://en.wikipedia.org/wiki/S.M.A.R.T).