How Cheap Can A PC Be?

geoff lane writes "Ballmer wants a $100 computer. OK, can we build a reasonable PC for just $100 and a copy of Linux? The rules are: It's assumed that a monitor, keyboard and mouse are already available. Ethernet connectivity must be provided. All components must already have Linux support. All components must be new and currently available. The result must be electrically safe for the home. Is it possible?"