Weird. I do not run windows on the machine so i have to take for granted your claims, but:
On linux, using Alsa 0.9.2 stable sound drivers and compiling an intel8x0 driver, the OS finds the realtek end. I can at a touch of a button or in command line move my stereo output to 5.1 Digital out and vice versa. No duplex tho. The intel sound chipset does support 5.1 out, the connector is Spdif ( coaxial ) or Fiber optic enabled ( old connectors ).
I am sorry to say that if the 5.1 doesn't works it comes from the window driver. I do have a nice red laser light coming out of the Spdif connector at the back of my lappy tho
I agree with the shelding and the hw used on laptop is never glorious so many manufacturers prefer a 'SB compatible 16 bits sound card' mantion.
Anyhow, the point i was trying to make do not bash the sound, instead put an eepro100 or a 3c59X 10/100 Ethernet in the lappy