For the sheer hell of it (I know this is an old thread), here are the results from my Quad Core machine running Vista:
The threaded version maxed out all 4 cores when it was running, the unthreaded didn't even max out one.
pi = 3.1415926535921401 count = 1000000000 time = 16083 threaded.... pi = 3.1415926535898211 count = 1000000000 time = 6817
The threaded version maxed out all 4 cores when it was running, the unthreaded didn't even max out one.