It depends on how you setup your wireless connection.
If your router is wireless, here's the deal.
If you get yourself a WET11 or similar device, or any other Gaming Adapter, it will work with the router (pertaining to a few config issues).
If you hardwire the XBox the the router, and hardwire the PC to the router, no need for any wireless config there.
If you have the XBox on a WET11 or similar device, or any other Gaming Adapter, and your PC is hardwired, XLink will work without you needing to set any options in XLink (you will have to setup the adapter on to the same SSID and channel etc).
If the XBox is hardwired and the PC is wireless, the connection method won't let you play games on XLink. It will let you connect and chat etc, but you are guaranteed problems with it finding / joining / hosting games.
I'm pretty sure the MS G Gaming Adapter will work over your current network, as long as you configure it to your networks settings properly.