The main difference is speed. B runs at 11mbps. G runs at 54mbps, 108mbps or sometimes a speed somewhere in between. Both run on 2.4Ghz up to 100-150 feet. You can pick up a wireless G router and some wireless G network cards to network your desktops and laptops. The routers have a built in switch that accepts 10/100 wired network devices. Use those with CAT5 cable instead of a wireless card for computers near the router. Use the same brand throughout your network. Linksys and Netgear are two reliable brands