PowerDVD installs codecs. Good codecs are often independent of the actual software, so yeah, when installing PowerDVD you also automatically enable WMP to play them.
(But you still wouldn't be able to use the many nice features of PowerDVD in WMP of course. And why installing PowerDVD just to play DVD's in WMP anyways? that doesn't make much sense
)
Oh and in my experience, WMP shows a total different (wrong) color temperature for some DVD's also. It doesn't respect (changing) aspect ratio's as it should. And the interface, compared to PowerDVD's is very clumsy (try to change scenes, languages, subtitles, sound codecs, camera angles, etc... it is very clumsy, if not impossible.)
in short WMP *beeps* for playing DVD's...
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