I recently upgraded my Black Macbook's Hard Disk to a Western Digital 250GB Scorpio. I simply went to Costco and bought a 250GB Passport External Drive for $140, cheaper than most online stores, and cracked open the case to find the SATA drive ready for installing. The enclosure has no screws and comes right off with a little force, and I put the Apple OEM drive (a Seagate, by the way) back into the enclosure and snapped it back together. It works like a charm. This is the easiest and cheapest way I can think of to replace the HDD, but then again I don't mind WD drives, as I understand some do. I recommend this method if you have a Costco nearby!