I installed vista business 64bit on an 8 core mac pro. I have some speakers connected to the analog out on the back of the computer. In windows I get no sound, but I do get sound from them if I plug them into the front headphone jack? I have the realtek audio manager installed. If I open it I see that there is a place to select analog outputs, but only when I have it plugged into the headphones jack does it show up.