I could answer this in several ways, based on your level of technical expertise.Simply put, you need a wireless router or access point. This will provide the "link" between your network and any wireless cards that are in your PCs. The PCs to be attached to the network are called clients.You can have either a Wireless B, Wireless G, or Wireless A network. G is backward compatible with B (meaning you can, if the router is set to "mixed mode") run a Wireless B laptop in a Wireless G network ... it will just run slower.There is also MIMO or 802.11n wireless, but this standard has NOT been ratified yet. You can run 802.11b or g clients with it as well MIMO clients.Additionally, it's 100% necessary to use some sort of encryption in your network. Otherwise people will be able to monitor your network traffic and pick up passwords, account numbers, etc. Obviously this is not likely to happen, but you can use either WEP or WPA and it's fairly painless. Note the word fairly.I'm going to give you a bunch of links in the Sources section that will help you in more detail.