Today was the first time I saw the below table references the new decoders in Windows 7 along w/ their known limitations. I think it will help answer a lot of people's questions on MOV and VC-1 support and what is natively supported
I found it reading Media Streaming with Windows 7 post from the Engineering Windows 7 blog. A good reference blog if you haven't read it before and some good info on transcoding as well.
Windows 7’s new “play all” decoders, encoders and transcoding capabilities
"If you have had any theories Microsoft was conspiring with the media conglomerates to protect their interests and not the user’s, throw them in the bin, pour jet fuel and remotely detonate them since Microsoft can’t be any bolder than building in DivX and Xvid native support in Windows 7. Yes, all your favorite Family Guy episodes will play in Windows Media Player. Yes I’m looking at you. You may have also heard there’s also native H.264 and AAC support. But that’s not all. After all, decoding is only one part of the equation.
In a presentation titled “Video Improvements In Windows 7” at WinHEC 2008, Microsoft also revealed new encoding and similarly transcoding capabilities in Windows 7. The new “Media Foundation” decoders are as follows,
In Windows 7, encoding is extended to widely adopted MPEG-4 and 3GPP standards with H.264 video and AAC audio encoders built in, on top of the WMV, WMA and MP3 encoders built-in to Vista today - after all, hardly anyone uses Windows Media outside of the Microsoft ecosystem. Speaking of which the Zune even supports H.264 and AAC natively.