Russ is correct, of course.
More specifically, though:
A hub re-broadcasts packets to all connections, while a switch only broadcasts it to the machine it's directed to.
A router is used to connect two networks. Basically a router looks at a packet & asks itself "Is this packet on my local network?" (whichever side it came in on) If the answer is yes, the router kicks the packet back out on it's LAN connection. If the answer is no, the router forwards it onto it's WAN connection, where the next router performs the same operation.
What you're probably looking for is a broadband router. There are numerous models available, with four port models in the $150 range.
Viper GTS