Carl,
When you say 1 PC should see the other, and not vice versa, what are you exactly looking to do?
Is this is at the browser level, like see local drives etc? Or is this application level? If you're in a M$WIN enviornment there are permissions and access level security that would limit visibility/access.
As far as access lists go, you've got to be careful. TCP connections for example, require 2-way communication. Blind 1-way ACLs might not get the desired results.
