I recently replaced the 320gb standard drive that came with my Mac Pro with a WD Caviar Black 750gb with 64mb buffer and 7200 rpm. I decided to return it because it was much louder than the original drive. It makes a sort of croaky noise whenever it it used and it keeps making brief little noises when it sits idle. It doesn't sound like it's breaking, but the noise is irritating and very noticeable since the boot drive sits at the front of the MP, which is next to me. The old drive was basically silent, but it was about 75% full and I wanted a drive with more room. I don't know if these WD drives are normally that noisy, but it didn't inspire confidence. Can anyone suggest a reliable, quiet 500-750gb 7200 rpm drive, maybe with a 64mb buffer? Are the Samsung spin points any good? Is Seagate a better choice? Is there any significant benefit to a 64 mb buffer over a 32 mb buffer? Could my WD drive have been faulty if it made such noises? Thanks a lot for any advice.