Some clarification here please?
Modem: Does it have a built in router? If just one output then it would be a modem only and a router is needed to coordinate the network traffic. A switch would work for hardwire but without the many options used in setting up your home network. Port forwarding, WiFi, security etc.
Switch verses Hub:
Hub- older technology, passes all requests and the PC or device have to look at all data and determine what is for them or a different device. (takes up device CPU time)
Switch- newer technology, keeps track of incoming requests and data then directs it only to the appropriate device thus saving some CPU time at the device end. This "smart" technology avoids "collisions" in the data stream.
Newest technology for switches is "megabit" support which is 10/100/1000 speeds.
So to answer your question you should get a router with the number of ports you need. Or depending your needs there are many options.