I got the same board, but I purposely chose it vs the 965P because it was the same price and has the built-in video that is VISTA compliant. It's nice to have if my regular videocard goes caput. As far as I know the two boards are completely identical except for that one addition. The built in video is disabled anyway if you have any videocard installed.
The other reason I got the 965G is that quite a few people (Newegg reviewers) were not able to post with OCZ rams installed on the 965P. This is a bios issue. I figured since the 965G is newer it would come with a newer bios preinstalled. I was correct on this and I was able to post with the OCZ just fine.
I just built this system just last night so didn't even have time to overclock. I don't see any reason why it wouldn't overclock just as well as the 965P, though. Truly the only way to find out is to setup your rig and try it.