I have a 300GB Seagate ST3300831AS SATA-II which is continously giving a clicking noise (loudest among 5 HDs I have in the computer - a couple of other Seagates among them) when reading/writing. The drive, however, works fine - for now. Should I get a replacement or is this normal? I am scared of losing 200+GB data without warning if it fails. Seagate's warranty replacements are refurbished units anyway 