On my PC, a P4 3.06, Media Player 10 does not play back 1080 WMV files smoothly. Power DVD does though, so I changed the file association of wmv files to Power DVD instead of Media Player and now I can at least view 1080 HD files smoothly.

Well Power DVD plays back the WMV files smoothly - unless they are protected with DRM. Those ones will only play back in Media Player so I can't yet view them smoothly.

I just figured out that Windows Media Player "Classic" (the old Windows Media player) plays the HD 1080 WMV files smoothly as well, but it won't play DRM protected files either. What's with Media Player 10's CPU inefficiency!?

I am seeing your results too. I have dual 3.06's with a ATI 9600XT. It never dropped frames with WMP9. I know where I can raise this flag.

One thing I've noticed is that when I go to the Media Player 10 preferences, the hardware acceleration option is greyed out and can't be selected. That may have something to do with it. There's a good chance that one of these days a regular Windows update will fix this, but for now it is kind of frustrating.

I am running another discussion at Anandtech. I have a suggestion on changing Tools, Options, Performance, Advanced, Video Acceleration to uncheck Use High Quality mode and turn off Overlay. I cannot try it as I am using a computer that does not have WMP10 loaded (and cannot play it without dropping frames anyway.)

I've tried all the different configuration options and still not been able to achieve smooth performance in Media Player 10. The older "classic" version of media player is better but still nowhere near as good as Power DVD on HD WMV playback. I'd be interested to know what other playback programs are compatible with HD WMV files, how they fare, and if they are compatible with DRM rights management.

I found the same. power dvd does play my high def clips better than wmp10. I only have a baby 933 p3. but I found this great player, it plays everything, and I even played a 1080p clip with only 4 dropped frames. its free too http://sourceforge.net/project/showfiles.php?group_id=82303&package_id=84358