The two nForce offerings, in particular, are interesting. From a cursory look at the images, it seems that the A7N266 does not use NVIDIA's integrated sound chip and NIC. Instead, the A7N266 has the C-Media CMI8738 for 6-channel audio and an optional integrated LAN/Ethernet controller. Moreover, the A7N266-E adds the Asus ACR audio module for S/PDIF input/output and skips the MCP NIC for a Realtek 8139. It seems strange for Asus to spend extra money implementing solutions that the boards' core logic chipset already provides. It also hampers having the single unified driver provide all the connectivity.
If you want an nForce board that only uses the NVIDIA integrated material in a non micro-ATX format, it seems that the MSI K7N420 Pro is the way to go.