Good reference source

I have a Dell XPS system with Vista Ultimate connected to ActionTec DSL Modem
with Wireless Gateway. I want to set up a wireless connection with my Gateway
machine running Windows XP, where only the Gateway and my Dell can access the
internet through the ActionTec DSL Modem. I have several online games that
will not play when the ActionTec with the wireless is connected. If I remove
the wireless one and put back the wireless ActionTec GT701 I can play my
games. What is a good reference to solve the problem or to correctly set up a
home network with just two computers where people in the area cannot use my
connection or share files with my DELL or Gateway.

Thanks.