typing this on the new computer! Replaced PSU; discovered that the failing PSU also killed my GTX560 Now I have a new PSU, run the computer with my old 9800GT and wait for 560 replacement.
560 replacement has arrived; have reinstalled the computer again, and am now FINALLY typing on it. And egads - SL is now running as if it was a TV show. With shadows, reflections and everything!