Hey Frang

I have the realtek 6ch on my Soltek and here's the deal. the center channel and the low frequency are actually supposed to be plugged in to the mic port so that the sub and center are pumped out through it. the line in port is for the rear surround speakers of course. Now, here are the things I did to make the surround features work.
1. have a source with surround audio output,E.G. DVD or game
2. check the 2 speaker boxes in the advanced properties as you've done.
3. check the video bar in the advanced tab in the sound properties so it appears on the volume control panel as well and turn them all up all the way.
4. configure the speaker setup in the Nforce panel as suggested above.
5. If playing a DVD make certain your software has surround option enabled as the version of PowerDVD that ships with many DVD drives makes you purchase an audio pack to get surround output.
6. If playing a game or something make certain you configure the audio in the game if necessary to use surround audio output.
I have good Sennheiser headphones because with a 3yr old around I don't want to damage his hearing with loud speakers or wake him up from his naps so I keep it quite around here and still rock out. However, I hooked up 2 pair of the Harmon Kardon HK-206's that I use for client builds, their the ones that come as the lowest option with Dells, and I had to either give up the center channel and LFE or the rear speakers. I suspect you will have the same problem where you loose the back surround or center/LFE using 4.1's unless your sub hooks up by itself using a seperate connector from the rear speakers in which case you can have the LFE output and just give up the center channel. Anyways, I hiope this helps you out and LMK if you need any more help with it brudda
EDIT: Hey Frang give
nvswap a go
NVSwap is an NVIDIA utility designed to help you set up and optimize your NVIDIA nForce audio experience. NVSwap tests and configures the setup of a 4 or 5.1 speaker system attached to the following qualified NVIDIA audio products:
* NVIDIA nForce2 with NVIDIA SoundStorm
* NVIDIA nForce with MCP or MCP-D
* NVIDIA nForce2 with MCP or MCP-T
* Any NVIDIA nForce-supported AC' 97 audio codec.
here's the
PDF user's guide