- Go to Start>Control Panel
- If you are using the default control panel view, click User Accounts>User Accounts
- If you are using the Classic view click User Accounts
- Uncheck the box next to Use User Acccount Control (UAC)...
- Click Ok
Maybe you don't want to disable this if you surf the web and download a lot of programs. Knowing what is attempting to install could be a good thing. But on a specific purpose computer like a Media Center, the UAC can cause more problems then it is worth.