Adding Boxee effectively gives Apple TV users a second operating system. A spokesman for the company says the intent is not to replace Apple's software, however, but complement it, by providing different ways to organize content. Users will not be able use Boxee to play DRM-protected content purchased from the iTunes Store, but can of course switch back to the main Apple TV interface.

Boxee is currently available in alpha form, so users must apply for an invitation on the company's website. Installing Boxee on an Apple TV requires Davilla's ATV USB Creator tool and a bootable USB flash drive. Apple does not support or endorse third-party add-ons, but the software can be removed by restoring the device to its factory settings.

Installation involves several steps: first, ATV USB Creator must be downloaded and installed on the flash drive. The drive is then inserted into the USB port on an Apple TV, where software is installed automatically when the device is powered up. After a restart, users can select Boxee on the Apple TV menu to download and install the media player software. After another restart, Boxee should be ready to use. Both applications are free. ATV USB Creator is available today for Mac OS X -- WIndows and Linux versions are expected next week.