Most games don't require your machines to be able to see each other's files. They almost all connect to each other through IP connections. As long as you have a router handing out DHCP addresses your machines should be on the same subnet allowing ip connections to occur.
You just need to make sure you don't have any static IP's. If you do, then make sure all machines on the network have unique IPs in the same subnet.
Just turning on file and printer sharing without thought of security is a bad idea. If you intend to share files among the machines that is a different subject.