For a starter ( w.r.t the age of the forum/community ) a free script or vB should do fine.
I am yet to see anyone using infopop in the starting stages, most of the communities using infopop are very active ones,atleast now... also all are remotly hosted ( i am not sure, if they give you the script with the source code ).
So start off with some free script like phpBB or anyother of ur choice ( tons of them out there ) or a vB and later switch over to infopop if need be.
Thanx