I'm surprised you got Feisty to install at all on a SATA drive. I had to use Kubuntu Gutsy Tribe-1 because of SATA driver issues with this mainboard, maybe I gave up to quick.
Beating the ATI/AMD proprietary drivers into submisson wasn't easy, there seem to be to much scripts, tools and utilities fighting over the config file. I ended up doing a: "sudo chmod 444 /etc/X11/xorg.conf" after editing it by hand, we'll see how well that holds up. So far I've gotten UI1 and UI2 with masking to work.
I have made a wiki page for the
Asus M2A-VM, It's not much yet, but I'm hoping other people with this motherboard will expand it a bit with their experience too.
Maybe we should set one up specifically for the problems with the ATI drivers as well? Probably won't be to hard to come up with a universal xorg.conf template that works on most setups. If you like I could post mine here for now as an example.