I read that you can actually also use the corner of a credit card. I didn't have a spudger and this worked perfectly for me. If you hold the card quite close to the corner and it has just the right amount of flex.
John, I didn't think of that. But yeah you are right, it would give it a lot more support.
I had a lot of trouble with getting those clips to lock in place again when reassembling. The way I eventually did it was to wedge something into the front of the CD/DVD slot so that I wouldn't warp the laptop casing. I used the end of a pen; when wedged in the tip of the pen was the right height to not support the casing above and below the CD/DVD slot and not allow it to warp.
I simply ensured the pen was aligned with one particular clip, lifted the laptop slightly, and squeezed the top and bottom edge of the laptop casing very firmly at that point. Each clip clicked in quite easily doing it this way. Just remember to move the pen (or whatever you are using) along to whichever clip you are clicking in.