I assume that the default port of the IIS is 80 and you haven't changed it.
From any other computer on your network, please run the following command in Command Prompt Window:
telnet <ip-addr of machine running website> 80
If you can connect from telnet then the site should also open in browser from this test machine.
If the port is blocked, the above command will fail. Then you need to change your firewall settings on the IIS Server machine [probably windows firewall if you are not using any 3rd party]
Hope this hepls