NIS 2013 - blocking access to network PCs

Hi,

 

I would like to block two network PCs from accessing my main PC. Am I correct in thinking that the NIS Network Map would be used for this, or would I actually configure the firewall?

 

Also, say I wanted to block all devices on the192.168.0 subnet, how would I go about this?

 

And finally, I don't allow any sharing on my network and don't need to access other shares, so I don't need Client for Microsoft Networks or File and Printer for Microsoft Networks. Would it be better to uninstall these protocols, or just disable them?

Thanks in advance for help/info/suggestions,

J