However (there's always a however right?), I'd personally be a little leery of combining both ATI and Nvidia boards in the same machine. Seems like if you were going to use both, or for everything on the board to have the proper drivers up and running, you would have to have drivers for both ATI and Nvidia installed, rather than just one of them. I could be way off base here so get confirmation.
I would opt for either a Nvidia based mobo or a mobo without onboard video. That way you don't have video boards from both sides of the isle all trying to get along in one box.
The ASUS M4N98TD EVO is a little pricier but is an nvidia chip-set with SLI support. That way you could slap another 460 in there in the future.
Hopefully someone else will chime in on the issue because there really may not be anything wrong with running the board you selected originally. I was just thinking, it should be possible to disable the card in bios so it shouldn't cause any issues.