Boxee provides a full screen interface for browsing photos, video & music stored on your PC or for accessing online media from sites like Last.fm, Hulu, YouTube & Shoutcast.

Download Squad did recently test the media center application & they came to this conclusion:

"Overall Boxee presents a slick media center interface which could be a compliment to Windows Media Center on Windows XP, Vista, or Windows 7 computers. While Windows Media Center provides a pretty decent solution for browsing and accessing media on your hard drive, Boxee's web video browser is far more sophisticated.

While Boxee doesn't work as a personal video recorder, if you have a TV tuner in your computer you can schedule recordings using Windows Media Center and configure Boxee to scan your recorded TV folder so that you can watch recorded, downloaded, or online video all from the Boxee interface without ever having to use Windows Media Center for anything besides setting up recordings."

Head over here for the complete review.

Official Boxee site