Realtek AC97 and Windows Vista Sound Issues.

Hi. The sound on my pc does not work correctly. I recently built this machine
and it has been working great. I built it in my old compaq computer's case,
using the built in front audio ports and card readers. However, I finally
bought a new case and it does not have front audio ports. (I didn't use them
much and didn't care if I lost them.) But now no sound comes out of the
speakers because there are no front audio ports plugged into the motherboard.
I know this because I took ports from another computer and plugged them into
the correct spot inside. Once done, sound came out of the speakers pulgged
into the back and if I put them into the new port it came out of there as
well. But I need to know why this is happening. I don't want to have audio
ports wasted inside the computer just so the back ports work. Any help would
be greatly appreciated.

I don't know if this would matter, but I'm running Windows Vista Ultimate x64.