Instructions
Turn off the Xbox 360, if it is on. Plug one end of an ethernet crossover cable into the ethernet port on the back of the Xbox 360.
Turn off the computer, if it is on. Plug the other end of the ethernet cable into an ethernet port on the back of the computer.
Turn on the computer. Let the desktop appear on the screen before continuing. Turn on the Xbox 360. Let the main menu come up on the screen before continuing
Launch your web browser. Download a networking utility program such as Winroute to the desktop. Double-click the file once it has downloaded to begin the installation. Follow the prompts to finish the installation. Quit the installation once it has finished.
Launch the networking utility program. Follow the configuration prompts to connect the Xbox 360 to the PC so that they can both share the PC's network/Internet connection.