If the drive is making loud clicking noises...the drive is most likely dying soon. I'd back up data, and then either wait till it dies or get a new drive. If it sounds like normal drive sounds (usually a "straining" kind of sound, and maybe humming), then it's nothing to worry about. I know in my old HP when I replaced it with a 320GB SeaGate SATA drive, it was making straining noises (but not clicking), and it still works fine..in fact, I'm using it in my current custom build right now, and it's been working fine for 6+ months.