I've never heard a hard drive beep! Until yesterday.
I just yoinked a free second hand Inspiron 9400 laptop for a media centre, sans disk. I purchased the cheapest SATA 2.5" disk I could find - 320Gb for about $50. I started installing MythBuntu and then the drive started clicking and beeping, and the installation froze! It was the usual crunch of a failing drive with an intermittent "beep" (much like the electrical interference noise you sometimes get in laptops / desktops). The drive worked fine in a USB caddy.
At a complete loss, I turned to the oracle (Google) and found this. Strangely, some drives are sensitive to the 5V power supply (it was the cheapest drive I could find).
Up until then I had been working on battery, so I plugged in the power, rebooted, and the drive worked flawlessly. Hopefully it won't do the same when I loose power...
update: The problem seemed to be getting worse, so I returned the drive under warranty. With the Christmas break I'll have to wait until they get back to me...
update: The drive was returned, and Seagate replaced it under warranty. For the same price I purchased a 320Gb Western Digital Caviar Black 2.5". It is infinitely quieter (I can't hear it with my head pressed to the laptop).
Live and Learn!