My MBP13" locked up one day and on boot up saw the blinking folder with question mark. I thought it was a dead harddrive so I ordered a replacement and upon installation got the same blinking folder. After booting up from the Snow Leopard install disc, the brand new drive did not show up in disk utility. That's when I poked around the web and saw the same exact issue on ifixit forum. I got the cable (a little high for a used part, no?) but it works so no complaints in the end.
I followed the ifixit web directions and it went very smoothly. The only thing I had trouble with was getting out the Two 3 mm Phillips screws underneath the harddrive bracket. I have two high quality #0 Phillips drivers and the screws ended up getting stripped. Had to gently drill out the stripped screws but in the end it all worked out.
Be careful not to strip the screws-- it is a pain in the @ss to drill out screws this small. If this happens use a rubber band between the drill and the screw (for more grip) and don't overdo it. Once you have slight movement, go to pliers to gently remove screws.