I don't know if you have found a solution to your problem, I have just the reverse. I have no sound from the speakers, but have audio when the headsets are plugged in. On a laptop that is working properly I show the exact same information in the device manager for the sound entry as nthe laptop with no sound from the speakers.
There is audio, so could one assume that the audio driver does work?
The lap top with no speaker sound will show a red X'd speaker icon on the task bar untill head sets are plugged in. show headsets with no speakers. Right clicking this and going to SOUNDS show only a headset ICON. On the laptop that does have sound fro the speakers and head sets the icon shown is only a speaker.
It would seem that for some reason windows 7 does not see these speakers. I a wondering if a reinstall would work to correct this problem.