I've solved my problems at last....don't know if the information would be useful for others.
My Corsair 2x 512MB XMS4400CT memory modules now work. Had to drive the vdimm upto 3V.
As for the network adapters, I'm just using the Marvel one and not the NVidia one. Network access is looking okay now.
It looks like one needs to assign a MAC address to the adapter. I've not read the online docs so I could be missing something.
Ran some benchmarks with SLI-DR, 3500+ Winnie, 1GB XMS4400, WD Raptor and Sapphire X850XT. All stock speeds and drivers from the disks:
3dMark01SE: 23342
3dMark03: 12123
3dMark95: 5732
1M SuperPi: 42sec
Any good? Looking to up the speeds of the FSB to 300, drop the multiplier a little (when I've upgraded the cpu cooler), and increase the speeds of the sapphire card.
Cheers