Silent PC Related Links

http://www.buildsilentpc.com/: First hit when searching for silent PCs. :-)
http://www.pcw.co.uk/personal-computer-world/features/2158556/feature-build-living-room-pc: Not specifically about silent PCs, but things to look for when putting them in the living room.
http://www.tomshardware.com/2004/10/01/athlonxp_underclocking_for_a_low/: Underclocking AthlonXPs to lower power consumption.
http://www.youtube.com/watch?v=63HyA11X9DI&mode=related&search=: YouTube video of a kid underclocking his AMD Athlon 64.
http://www.cpuid.com/clockgen.php: Link to the Over/Under clocking program he was using.