Why in the world would someone want to cram a fully-functional PC inside of something like a classic Gameboy? Because it's fun, that's why!
more pics after the jump
The cool thing is that the little system will actually run Windows XP off of a Compact Flash card. I would assume Linux would work just fine as well. You'll need to hook it up to a monitor to see what you're doing though, it looks like they ran out of room to install one into the Gameboy. As cool as that might have been, it wouldn't have exactly been practical anyway.
He has even replaced the A and B buttons with LEDs to show power and activity. It's attention to minor details like that that make a mod really stand out.
Gameboy XP PC [via plasticbamboo]