Istoops - Ning is quite a good system but you might consider building a Facebook group first.
Here`s why. When you create a group, a community, the most difficult challenge is getting people to start communicating. If visitors come to the community with no comments they assume nothing is happening there, will not join and your idea fails to get traction.
On the other hand, with facebook the creation of community is much more viral by nature. You start by creating your presence, find and make new "friends", join other groups and comments, then create your own group and invite your `friends` to it.