How much of a problem?

[LongRunner]

As of now, my ST31000528AS has 14 reallocated sectors, 2 seek errors, 8 "reported uncorrectable errors", and 2 high fly writes, after 26,675 hours of runtime, 1240 start/stops and 631 power cycles (on Seagates, to my knowledge, the start/stop counter excludes power cycling).

Still have yet to encounter any problem with either WD800JD-00LSA0. As for the ST31000528AS, one of the more annoying things it's been doing recently is seeking for short periods at seemingly random times. Wouldn't be quite so bad if it wasn't such a noisy seeker (I don't have a swap file on it for that reason).

[c_hegge]

Keep an eye on those re-allocated sectors. If you get any more of them, it's probably time to save your data and replace the HDD.

[LongRunner]

It's getting worse — up to 22 now (at 27,759 hours, 1,262 start/stops and 638 power cycles). The WD800JD-00LSA0s are still fine, as I expected. With my new-PC-to-be will come a trio of 3TB WD Caviar Blacks (WD3003FZEX to be specific); overkill maybe, but they were the best value (with the 1TB version at $95, the 2TB version at $175, the 3TB version at $225, and the 4TB version at $309 — from PC Case Gear) of the family. It could indeed be another 8+ years before the upgrade after that one, and hardware with a Life Span of Ages is the way I like it.