Great directions. The 250 GB Segate in my 2133 failed SMART (two years old) so I replaced it with a 1TB WD Blue drive.
Pull the temperature sensor cable for the optical drive well out of the way so you don't trap it when inserting the new hard drive.
During reassembly make sure not to trap the cable for the temperature sensor on the superdrive -- it goes on top of the new hard drive.
Rather than disconnect this cable, you might as well jump ahead to steps 19-21 and remove the sensor from the drive.
During reassembly, make sure that the data and temperature cables will reach their sockets before inserting the eight screws.
Removing these screws was the most difficult part of the whole job. They were tight and felt as if the heads were about to chew up. I had to press really hard and jerk the screwdriver counter clockwise to loosen them. Despite others' warnings, I managed to drop a screw when reinserting.