Wireless Router

Get a wireless router (about $8 after rebates from CompUSA). If all of your PCs are very close to the router location, you can connect your PCs to the router using network cable. Otherwise, get a wireless netwrok card for each of your PCs (about $8 after rebates from CompUSA). Then, you can connect all your PC to the router wirelessly. The installation instruction coming with the router is good enough.