Hi and welcome to the forums
Yeah, it's still a pretty active forum, and probably the most active Fallout: New Vegas forum out on the internet, considering the game is now about 2 years old.
Anyway, since this isn't really about Fallout New Vegas, I'm closing it. Also, if you want to introduce yourself, please do so in http://www.gamesas.com/topic/1358208-introduce-yourself/, thanks.
New Vegas has far more topics and views than Fallout 3. We have some passionate fallout fans and that's what keeps me here.
A large reason for this though, is simply because Fallout 3 is an older game. And older posts tend to be pruned away eventually. It doesn't mean it was less active during it's heyday. It's very hard to now tell which one had the most active forum for the first ~2 years after the game launch or whatever.