Consider your wireless adaptor as a second NIC.Taken from MrRobinsons guide. there is a link to the full tut in my sig.
Setting up Configuration 2
The configuration 2 diagram above shows the most common setup you would have with 2 NICs in your PC. The only difference between this and configuration 1 is that the second NIC would have a connection to the internet for you. Chances are this NIC to the internet is getting a public DHCP address like 126.96.36.199, or any such number. If this NIC goes to a router, you may wish to read configuration 3 and you may not need your second NIC at all. So when the NIC gets DHCP like this it is automatically assigned an ip, subnet, gateway, dns, etc. so you don't need to do anything else to it. The only "gotcha" with this configuration is that when you configure your second NIC that goes direct to the Xbox you may configure it in such a way that your computer tries to access the internet through that NIC instead of the correct one with the public DHCP. This is a routing issue and one way to ensure this doesn't happen is to configure the NIC with the connection to your Xbox exactly as in configuration 1, specifically making note that you DO NOT enter a gateway address. Your Xbox itself can also be setup just as in configuration 1. Refer to the Troubleshooting section if you are having problems and yet are set up as I described.
So if you connect one of your NICs to a router in this configuration you may be getting an internal IP like 192.168.x.x instead of an external IP address. If this is the case make sure the NIC that goes out to the Xbox is not given an IP address on the same subnet as the NIC going to your router. For example, when the NIC going to your router and out to the internet is getting an IP of 192.168.1.x and has a subnet mask of 255.255.255.0 and the gateway on this NIC is the IP address of the router, then set the IP address of the NIC going to your Xbox to 192.168.0.x with a subnet of 255.255.255.0 and don't enter a gateway. Then make your Xbox have an IP address on the 192.168.0.x range, and again a gateway would not be needed.
**Advanced Option** If for some reason you would like both your NICs on the same subnet then you can still force the one going internet to be used by default for everything and the one going to the Xbox to only be used when connecting to the static IP of your Xbox. Open up a command prompt and type 'route print'. With route print you can see what route your data packets will take to try to access the internet or your Xbox. What you can do is manually add a route that tells your computer that anytime it tries sending anything to 192.168.0.3 it should use the NIC with the direct connection the Xbox, not the one that goes out to the internet. To do this run the route print command. The first thing you'll see is an interface list. It'll say something like:
Interface List 0x1 ........................... MS TCP Loopback interface 0x2 ...00 06 5b b8 e3 33 ...... 3Com 3C920 Integrated Fast Ethernet Controller 0x3 ...00 02 2d 26 2c 74 ...... Dell TrueMobile 1150 Series Wireless LAN Mini PCI Card
So in this case the NIC going to the Xbox is 0x2, which would be IF 2 in the command. To add the static route follow this pattern:
route ADD 188.8.131.52 MASK 255.0.0.0 184.108.40.206 METRIC 3 IF 2
destination^ ^mask ^gateway metric^ ^Interface
So in our example you would type:
route -p add 192.168.0.3 mask 255.255.255.255 192.168.0.2 METRIC 1 IF 2
to remove this at any time you would just type:
route delete 192.168.0.3
The other option you have if you want your Xbox to get out to the internet through your computerís internet connection is to set up Internet Connection Sharing (ICS) on your computer. How to set this is up a good thing to google search. You can also try this page: http://www.xbox.com/en-US/live/connect/windowsics.htm
for good details. Once set up the only thing to change is to put a gateway address in your evox.ini, avalaunch.xml, or mxm.xml file which should be your computerís IP address, so the gateway you would use is 192.168.1.1 since that is probably what ICS will set your NICs IP address to.