I love the idea but wouldn't it be cheaper if you just added more ram to the system and partition it as a RAM drive?

The only caveat is the loading of the OS onto the RAM drive on bootup, but once its up, any reboots would near instantaneous, no? Can set the system to low power mode (turn off hd, throttle cpu and gpu, LCD) to sleep.

I would think a 2 GB stick would rock as a swap file or setup the system as a dedicated file server.