Do you really need to AIM though? You have VATS.
Anyway, did Nelson in New Vegas, and then did the Ranger Station Charlie stuff. Legion is suitably creepy.
Kind of would not mind tying Fallout 3 but my experience with Bethesda's games has been... Okay they're pretty much my least favorite game company. And I've heard that FO3 has some of the Bethesdaish things I don't like, namely a complete lack of economy when it comes to worldspace (lots of needlessly big and empty buildings; lots of dead space).
I didn't like Fallout 2, for that matter (kind of for the same reason Bethesda's games bug me -- FO2 was huge and very, very messy for it), so I'm actually not aware of most of the lore in the series since I guess most of it came from FO2 and not 1. I thought the NCR was something New Vegas came up with.