[quote name='Quackzilla']Are you oblivious to physics?
Clamshell designs do not protect impact damage at all.
Following Newtons first law of motion, inertia, the internal components will stay in motion after the unit hits the ground. If they are not properly secured they will break.[/quote]
Do you know what inertia is? It means that if something is moving and has nothing to slow it, it will tend to keep moving. In this case, Newton's First Law says nothing about what will happen with the unit hits the ground because there was a force applied that interrupted the motion, but I digress.
What I really intended to say here was thank you for proving a point I intended to make: If the PSP falls, it will get

ed up. Any moving parts would get jolted out of alignment from such a fall, which is a problem that neither the DS or the SP have due to the fact that they have no moving parts.
Oh yeah, and if the unit isn't on, in which case the chance of moving parts getting screwed up is lessened, the screen would get scratched, whereas a screen protected by a clamshell most likely would not, unless the fall was so great that, upon impact, the unit sprung open somehow and a screen got hit.