[Super J]

i just upgraded my machine back to vista for good this time.  but since install i have noticed some things.  every program that reads cpu data only shows one core, cpu-z, even taskmanager, but still shows as a core 2 duo.  i was wondering if anyone knew what could be going on.  it was most noticable to me when i went to run a bench and my fps in the bench were cut in half.  please get back to me asap if you have any clues.  about to get and e8400 but want to know if it is a vista thing or maybe the mobo is bad or something.