You need a Broadband Wireless router and a wireless network card in each machine. Within the range of the router, you can wander about with your laptop to your hearts content.
With this investment, don't be tempted to cut corners. Security is a big issue with wireless equipment, and some time searching out information will pay dividends. For example, make sure your chosen router is capable of acting as a firewall in addition to the chosen tasks, and will support at least 128 bit encryption. Although there is some conformity within wireles standards, the main being the theoretical transfer rates and transmission frequencies, not all equipment from DIFFERENT manufacturers will work together, so buying from the same manufacturer for all your components may save some headaches.
Don't forget, DON'T try and mix different standards.