xtempo:
on your question in the other thread, you do not need to buy SMART Utility, because the buy-version has no additional feature (such as removing bad sectors). The demo just stops working after 5 launches or 28 days, whatever comes later!
Tech Tool Pro is able to reassign bad sectors (that is, replace them with reserve sectors), but it is not for free, maybe you can find a free download somewhere...
You can try, if the bad sectors get reassigned, if you save erase the drive, i.e. format the drive with disk utility and choose "write zeros 7 times". It takes a while, you can also first try, if they "disappear", when you write zeros only one time, first.
You say, the capacity is showing right now? Did you google or look in Seagates own help Forum, if that special drive model has this as a known issue or is in their list of drives with bad firmware?
The chance to get a bad drive is statistically 0,003% per user, but if this is a model related problem (look Seagates support page), you might want to replace it, if it doesn't cost you anything. Even, if drives can last with bad sectors without going worse over time. (I have two myself, but they were used already, so I kept them, but I do use them only for the OS in my PowerMac G4 and keep the personal files that are worth something to me on a second drive, just in case.) - on the other hand, you will not know, if a replacement will last, too. But chances are good, that you do not get a bad one two times
Although there is no clear indicator, if one manufacturer is better, if you look at xlr8yourmac.com in the HDD-database, you find that Hitachi and WD drives get the best reviews, while Maxtor/Seagate reviews seem to talk about these drives having caused problems from time to time, when upgraded in a PowerMac G5. But that was some years ago. (Hitachi is no more, but you can also look for Toshiba). That said, you could still do well with a/your Seagate.