My Burlinstien has 2 FW Bays a Seagate 7200.7 500GBer and a 120 GB Seagate. The 7200.7 500GB makes a lot of noise but only/mainly reading/writing data. Seems louder recently? A lot of click click click click. It is my primary backup drive. It is backed up to the 120GB. It was a boot drive when new.

How much click click click is to much. Since it is backuped I was thinking of zeroing it out. (I've never zeroed any drive)

The drive has always had some clicks while reading/writing data. I never heard my other Seagates 4 or 5 sound that loud. It a mechanical sound - I think (not as in a bad drive) but just working. It's quiet when idle. Maybe it's just because the iMac's quieter and it sits closer to me things seem louder.