Dell :: M1330 (Windows 7): Two Audio Outputs, Only One Works

I recently upgraded my M1330 from Vista Home Premium to Windows 7 Professional, and I've lost the ability to use both audio outputs at the same time.

For example, on the front of my laptop, there are two audio outputs, so that two people can listen to something at the same time.

However, after going to Windows 7, I've lost that ability. Both of the outputs work, but you cannot use 2 headphones simultaneously.

I used the SigmaTelHD Vista drivers and no luck.