Yes your network is the PC and the Xbox, if you enabled mac addressing then both of those units mac addresses should be allowed in your router. Also if you have a smartphone that uses wi-fi when available then you will want to allow it's mac address as well.
Please note, I was not telling you to enable mac addressing, simply asking if you had. Mac addressing adds security to your router because then only computers with the addresses specified may use your router (helps keep the neighbors from using your bandwidth). You still also need to be using encrypted transmissions,
WPA-2 level is recommended. (
WEP is far too easy to crack) But with WPA-2 and mac addressing your network will be safe from the average neighbor, so if you have it on and all your devices can still connect to the internet then your network is set up in good shape.