For the time being, it sounds like you just need a bit of networking advice? If not, please feel free to disregard and reclarify your needs:
First off, how is this "old PC" on the network? Is your router forwarding packets to that box when a port 80 request is made (a port 80 request is made by typing http://192.x.x.x
into a browser, where 192.x.x.x is the IP of the box you want to request the http from)? Can you describe your network? Be sure that you don't have a firewall on that redhat box blocking port 80, for the http requests. Be sure Apache is started on the box as well (follow the millions of guides available on ensuring apache is started correctly and that it's running).
If none of this helps, please feel free to post back up with answers to the above questions as well as any other pertinent info you may have