Firewalls and Security issures?

hello again all,
well i have a new job set in my lap for the future. i have to network out floor that is cake, but the fun part is that i will have a network ring of about fifteen pc’s and now they want me to set up a website and host on an extra standalone pc. now what my question is i obviously won’t put it in the ring of hte network but pull it off before it hits the ring. i need to set up a firewall to keep people from getting into my pc”server” or onto my network is this possible.????
t.i.a.
questionable?