Wait. I'm looking at the interior photo of those hush PC's, and I don't see the CPU up against those heat sinks on the side. In fact, those heat sinks look like cosmetic decoration to me because they're not connected to anything inside the case.

They aren't purely for decoration. If you look again you will see that the CPU is covered with a shiny bit of metal and that bit of metal is connected to the right heat sink by some funky new heat pipe. On the other side the HD carrier is connected directly to the heat sink on the left.

This wouldn't work with a P4 I don't think though, these EPIA processors really don't generate much heat (but then they are lots slower than the P4s).