I am using Vista 64.
I also bought a seagate 640 gb 32 mb cache HD. I just reinstalled windows onto it, and all is well. Realtemp shows 4 cores, and so CPU-Z shows 4 cores and 4 mb x2 of cache. Temps are low with my arctic cooler 7... all four cores are between 29 C to 34 C.
Now to overclock!