Try downloading the Media player codec packs from cnet.com.
WMP12 won’t download codecs from microsoft automatically but third party software can still be added.
Frankly after recently changing to Windows7 I have come to the conclusion that I have WMP@ 12 almost as much as I loved WMP11 on an XP system.
I have found it all but impossible to get WMP12 to display albums in chronological order unless I manual tell it to each time I go into a particular artist file.
WMP11 (atleast in XP, I never tried in Vista) could be set to do this automatically.