I'm not to sure on this but,
If you use the networking setup, there are I believe three (3) options to chose from, be careful to chose the correct setting that says (something like) "This Computer connects through another computer"
Those are not the exact words but something similar.
Also make sure all of the PCs have the same "Work Name" IE: MSHOME.
Yes, WAP is one of the types of protection used in routers.
What OS are you using, is it XP or?
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edit.
Actually I think I may be going up the wrong route for what you want, but no-doubt one of the other "more learned more knowledgeable folk" on here will step in and come to your rescue soon.