Windows Vista Microphone does not work - Vista Home Premium

I had the Vista HD Audio driver installed and updated to IDT as it is an Intel motherboard. There is not a very good manager with IDT but it says it is connected. I tried front and back jacks and every combination available. The mic does not work. I tried installing Realtek AC97 for Vista but it says it's not signed and will not accept install it anyway. I tried every permission I could think of to no avail. The mic works fine on my XP SP2 computer but not on the Vista one. Any ideas?