A quick note about a hard drive: I just replaced the internal hard drive on my 15" MacBook Pro (model A1211) using the procedure at iFixit.com. So far, I'm thrilled with the new drive, a 2.5" 500GB, 7200 rpm, Hitachi Travelstar 7K500 SATA drive with 16MB Cache (Model number HTS725050A9A364).
The performance is noticeably quicker than the 5400 rpm model that had been in the laptop, and, icing on the cake, it's very quiet, too. I could just barely hear it over the laptop fan noise when the drive was doing sustained writes. Highly recommended.
I bought it from Other World Computing, which bundled the drive with a simple toolkit (Torx T6, Torx T8, Phillips #00, and 1.8 mm Flat screwdrivers, and a nylon spudger) and a USB 2.0 external SATA drive enclosure for approximately $125. Altogether, not a bad day in the workshop.