Maybe I missed some instructions somewhere, but my machine has been acting erratic and generally not working. A big clue was my PWM frequency not being correct. Turns out there's a setting in Vista under control panel, power management, advanced power settings. Expand the tree and find "Minimum processor state". Make sure this is set to 100%. Also do the same for maximum.
Once I did this, my PWM frequency is correct and things work better than ever!