I phoned Stak who supplied everything and it seems the 939 socket MBs are
obsolete.

Not sure if you've heard of Freecycle, but it's a message board
service set up in "local" areas, where rather than throw stuff out,
you offer it for free to people.

PCs are *always* appearing on the one in Liverpool, perhaps finding a
local group might get you a close match for what you've currently got.

http://www.freecycle.org