Spoke with tech support at the mobo manufacturer - they agree with the firedog muppets....there should be some life from the black socket.
Diagnosis, faulty board. RMA.
Black Screen of Death prevents doing *anything* on new machine.
Spoke to video card manufacturer, they say "Vista cannot *install* with over 3gb RAM, reduce to 2gig, re-install from zero (reformat drive), switch off an put all memory back in".
"Known issue", he says. Let's try that then, eh?