I believe My power supply may be the cause as I have a fresh i stall of win 7 with all the latest drives and updates. Its a win power and I've had it about a year. It says 800watts but I don't believe that in the slightest.
It would be more than sufficient, but I don't advise it unless you plan on a dual-GPU setup; a cheaper PSU like the OCZ StealthXStream II 500W or the Antec NEO ECO 520W would be plenty for a single-GPU setup upto a GTX 460.