unfortunately its not quite that simple...alot of people re using NAT routers these days for DSL connections to all thier pcs in their homes and offices.
Unless you are MSCE you most like(I said most Likely), do not know how to force an IP. Also no matter what you say people will not risk thier systems. this is a unfortunate result of the few out there who find it necissary to play GOD and attack computer systems for thier pleasure. They make no real dent in Corporate America or the world but they believe they can control all, see all, and know all. Thier selfish idiots not unlike most terroist in this world.
So in the present state of affairs you see there is no real solution.
Some of us are trying to be as fair as possible.
In my case I will place a down load /upload pc in front of my fire wall for sharing...but the fact remains again that few of us have the need , desire , or capitol for this approach either.
I feel your pain.