The trick is to turn on legacy boot ROM support. Simply enabling the NIC and setting the boot device to "Network" is not enough. Weird.
I haven't tried it without the GT430. It might be OK and it would certainly use less power. I expect the video board is soaking up double the power of the mainboard.
I've only been using the system for an evening but so far, it has been perfect. ... as you would expect.
It's replacing an old 2GHz Athlon X2 system with a GT220 card and I can't say I can tell any difference. Both have worked perfectly. I expect both systems are heavily over powered with the nVidia hardware. Without the nVidia cards, I would imagine both systems would just barely manage HD decodes and would experience the odd glitch.
Oh yes... the audio came right up without configuration. I'm using s/pdif.