Most Windows 7 editions include the codecs for natively playing back many standard video formats, including .mov, DivX, and DVDs. (Starter and Home Basic omit this extra.) If you want to watch a movie, just pop in a DVD and start it with AutoPlay options, or within Windows Media Player or Windows Media Center.

Blu-ray discs don't work natively in Windows 7, so you'll have to add Blu-ray-capable software, such as CyberLink PowerDVD or ArcSoft TotalMedia Theatre. You can watch high-definition discs within those playback applications, or you can launch Blu-ray discs from within Media Center. (Media Player only works with DVDs.)

Activate Media Center after installing the necessary third-party software; then navigate to the heading, and activate that third-party option. If it's the first time you've played a Blu-ray movie, the extra software may still launch to complete installation. Otherwise, you can watch the Blu-ray disc from within Media Center.