I flash upgraded my BIOS to version 1.60 which was released a few weeks ago. Upon rebooting into Vista everything was redetected by still no network. Looks like I'm going to have to do same thing you did and just pop in another NIC.
Works perfectly under Linux though.
^2
Oh, and turns out my mobo is actually the Asrock K8NF6G-VSTA which has a 754 socket instead of AM2. They both use the same nForce 405 chip though.
ASRock Motherboard - Download