Bummer. We’ve got an older 1.4Ghz Athlon PC here in our family room and Silverlight does not run on this chip, according to this thread: http://silverlight.net/forums/t/5590.aspx
Someone should update the Silverlight system requirements, as there’s no mention of this. That page says all you need is a “X86 or x64 500-megahertz (MHz) or higher processor with 128-megabytes (MB) of RAM”. Apparently, Silverlight needs a processor that supports SSE instructions, witch the original Athlon chip lacks. AMD added that feature in the Athlon XP.