Bad sectors does NOT always mean a dying HDD, several things can cause bad sectors, badly fragged data can sometimes lead to bad sectors(these can be corrected with a proper utility) others are actually bad physical spots on the platter and can't be fixed(although HDD Regenerator claims it can fix even those)
Most of the time when I find bad sectors on a disk, it is fixable with HDD Regenerator and many of these drives have been working perfectly since the repair for over a year.
My advice is to get a copy of HDD Regenerator and run it on the drive(it doesn't affect data on the drive when it does repairs) If it can RECOVER the bad sectors, I'd not worry too much, but if it FIXES(by writing them out) the bad sectors, then I'd replace the drive. Personally, I'd not want to use it to hold my system partition after that anyway, but my experience has been that "fixed" drives will continue to work for quite a while, especially if they are good quality brands to begin with, and if they can pass a recertification test(you can probably download such a utility from the HDD manufacturer's website) If a drive passes recert, it means it is good(according to most drive manufacturers)