GalCiv2 is a great game and worthy of being mentioned along with Civ IV.
I'm not sure about a GalCiv2 forum here since this site is tightly focused on Civ (and IMO the best Civ site). Couldn't hurt, I suppose, but it doesn't seem to fit. Not to mention that the official GalCiv2 site is very well done and they have their own busy forums. It's not like Civ IV's weak site and almost complete lack of interaction with customers/users.
GalCiv2, while having sweet graphics and interfaces, isn't as much of a resource hog/mess compared to Civ IV, IMO. A beefier system is always better but despite GalCiv2 supporting tons of high end graphical features you shouldn't have any problems at all if you can run Civ IV at all.
Stardock, the makers of GalCiv2, are exceptional at communication (you see them on their forums a lot and can catch them in IRC - at least you can so far - I'm sure it'll taper off after a few weeks). They are also exceptional at supporting and enhancing their software - I'm sure there will be countless patches to both fix bugs (there are always bugs), to add user requested features and changes, and to simply add more to the game.
Stardock is both the dev and the publisher, which gives them the freedom to continue to support and expand the game very robustly, which they do, and it shows in a BIG way.