ace11, you'll only need a switch with more ports than computers. Try to find a high quality one.
I assumed you want to connect into network using wires, that means ethernet cables. I also assumed that those computers need cables shorter than 100 meters, they are not further than 100 meters from the switch/router.
To have internet connectivity on all those computers you need a cheap router if you don't need to have many simultaneous transfers. When I say cheap I don't mean a 20 dollars router, a "for home" router. A "pro" router and a good quality switch. Please see Cisco offer for example.
I agree with TheEmperor.