I believe both boards are much the same, with several cavets. First off, the LAN does not really count - I've seen different revisions of the same model of motherboard have different LAN chips - in fact, the CD that comes with the m/b has all of the different LAN chip drivers, and just uses the one that is actually installed.
So, other than this, the 2 real differences is that the AU13 has the optional SATA interface available, whereas the AU11 does not. Lastly the AU11 has a considerably different layout, because it is an earlier design. If I had to choose between these two, I'd get the AU13, even if these was a few dollars price difference. But until they make a dual channel nForce2 m/b that has the extras of the AN19E, I'll probably wait to move to a new board. I find that the KT400 chipset gives much the same performance of the nForce2, with the exception of not being dual-channel, of course.
