If you're updating, then go for updating your kernel to version 2.6.2 or higher. As of kernel 2.6.2 you can go for the forcedeth-driver!
I've tried it myself with ML 9.2. After install I had to compile the src.rpm driver to get the onboard NIC working, but after updating to kernel 2.6.3 it worked perfectly with the forcedeth-driver.
I'm now on ML 10.0 CE with kernel 2.6.3 and my NIC works out of the box.
You have to pass a line into your modprobe.conf:
alias eth0 nvnet