I just ordered a nforce2 board.
From what I understand - the audio drivers suck ascii but the commercial open sound system (I think that's what its called) drivers can be had for about $20.00 and work very well. From what I've heard. I'll find out soon enough I guess
Ethernet - I thought I had heard about problems with nforce1 ethernet but I think that got fixed with updated drivers from Nvidia.
USB2 - I think for USB to work to have to use the drivers supplied by Nvidia. I'm not sure though.
If that is the case then hopefully it will get into the kernel in the future.
I have zero idea how well the iEEE 1394 works (I got the deluxe board) if you get one with onboard FireWire. I won't be testing that on my system for at least a month, probably more.
Hope I was at least of some help ...