Hi Patrick,
As we know that Blu-Ray is a patented technology so it requires appropriate codecs to be purchased and hence we cannot include it in our Operating System.
To play a Blu-ray Disc, you need to use a non-Microsoft program that supports Blu-ray playback and a device capable of reading Blu-ray Discs.
Check the below link:
http://windows.microsoft.com/en-US/windows7/MPEG-and-DVD-video-frequently-asked-questions
Hope this information is useful.
Amrita M
Microsoft Answers Support Engineer
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