AA isn't realy nececary in most games, heavy performance impact wit nearly no visible improvement (except far distant views etc...)
Your setup will be sufficient for the most games. With my GTX280 Metro runs smooth (but with a bit low fps). But in metro you also can't fine tune the settings (Grr console games...)
Some games will be limited by your cpu, witch model is it? E8400? my E8400 runs good at 4Ghz, cooled by a Scyte Mugen. So you may want to consider OC for some extra bang, if needed
Fallout new vegas will most likely use the oblivion engine in a updated variant, no danger for your system here
for the other two I have no information, but since all game developpers are currently freaking out about console games I don't expect exordinary demands...