I have a Rev A. with 80GB platter-drive and the 1.86 CPU. For the past six months or so, sometimes when turned on or woken from sleep, the HDD makes a ticking or a screeching sound. The first time it became REALLY LOUD I started doing Time Machine backups but rather than be without a computer, I decided to ride it out until the thing finally crashed. Last night it makes the screeching noise (sounds like an owl screaming it's head off, no, not hooting, screeching) for a good 10 minutes. I got another backup off and shut it down. I have a Genius Bar appointment for later today and I know for a fact that they have the part in stock. What do you think is wrong with it, how long will I probably have to wait AND, best question - if I pay the difference for the 128GB SSD, will they replace it with that instead?