If it's a t1 you will need a router which can act as your dhcp server and firewall also if you're not too nervous. You can get a Router with a TSU/DSU built in or you can use an external one, but you will need one. ISP may provide both, but I prefer to provide my own. Then the router should connect to a switch and your PCs to that. Cheap dumb switch is fine for 6 PCs nobody uses hubs anymore. With XP, you have to manually enable sharing and make sure they are all using the same workgroup name. That's pretty much it.