I managed to get NetBSD 3.0.1 to install over NFS onto the ASUS 
P4R800V PC (took < 15 minutes for full install from mounted 3.0.1 
release directory).

First boot was a problem with screen filling up with continuous lines 
of:
  auixp0: codec read timeout (reg 26).

I disabled auixp0 at bootup and compiled a kernel without that 
driver. The dmesg output now shows a couple of devices as not 
configured:

ATI Technologies SB200 SMBus Controller (SMBus serial bus, revision 
0x18) at pci0 dev 20 function 0 not configured
ATI Technologies IXP AC'97 Audio Controller (audio multimedia) at 
pci0 dev 20 function 5 not configured

Any ideas as to how to get both these or at least auixp0 working.

FWIW I've checked throug backup of previous FreeBSD 5.3 on this m/b 
and find similar with both being detected but neither configured.

I could buy a pci soundcard but I'd rather avoid that if possible.

David