What you'll need:
- Ethernet cable (Comes with your console)
-ANY PC with regular Wi-Fi adapter and it needs to be placed quite near to your console
-Xbox 360 console :O
Press the shiny little Start button on your screen
Type: "Internet Connections" in the search bar and hit enter.
Now you should see 2 connections
Hold your left button and highlight both of 'em, then press "Bridge Connections"
And now you should see a little modem icon with a name "Network birdge"
Now just connect to your wlan with your PC and plug ethernet cable from your PC to your console! Voilá you're done!
Now just start up your console and "Test Internet Connection" or something and you should be online! Hope you enjoyed!
PS. You can also connect to your PC now from your console with this little trick and watch movies and stuff directly from your PC.