NBC has launched its online video hub for the 2008 Olympics, which features free on-demand video for over 20 sports. In order to maximize quality, the videos are available as downloads (you can start watching before the download finishes) and will be in “up to HD” quality. Unfortunately, the video downloads will only be available on Windows machines running Windows Media Center – once again Mac users are left in the cold, likely because of DRM issues (and the fact that Lenovo and Microsoft are sponsors).

While the Olympic ceremonies don’t kick off until August 8, NBC has already posted footage of Olympic trials. Once the games begin, NBC expects to have the footage available around 12 hours after each competition (which shouldn’t be too annoying given the time difference).

Microsoft is participating in the partnership, so access to the videos will be integrated into Media Center’s main panel. Users can also visit this TVTonic page, and the content will be available directly from NBCOlympics.com beginning next week. You can read more about the service at the TVTonic blog post here.