Never ever ever get a hub anymore, their pointless now with the invention of switches.
For every network, you should* be using a router. This is what makes the network tick, and allows you to have one. A switch or a hub does not allow you to have a network by itselfs*
* refers to you may choose to do something weird if you know what you are doing, and that with terminal servers and DHCP servers and crap you may not use a router.