There are some .mov files it will play, so don’t give up. Windows Media Player as part of the release candidate (RC1) will play some types of .mov videos. It depends on how the .mov was compressed.
You may have noticed that there are some types of .avi that will play with Windows Media Player Classic, but won’t play others without the correct CODEC installed.
I suspect so far Microsoft have made a concious decision with the release candidate of Windows 7 (RC1) not to play .MOV files from within Windows Media Player.
One of the many great things about Windows 7 is that Windows Media Player can play an assortment of movie files including .avi’s encoded as DIVX or XVID without the need to download and install a codec pack such as K-Lite.
With the imminent release of the retail and oem versions of Windows 7 later this year I suspect it might just be a licensing issue rather than the fact that they have just not got round to it yet.