Im not completely familiar with all the ins and outs of WMP12, since it is not my default music player.
But ..
What you can do is create a new library for your christams music or any music you do not want in the main library all the time.
1) On a location on your HD, (Anywhere EXCEPT the My Music Folder) make a new folder and name it however you see fit.
Inside that folder, Move all your Christmas Music, and other Music you do not want as a part of the 'main" library. And Delete it from the My Music Folder if you need to afterwards.
2) From the Start button, click your User name, and in the left panel
"Right Click"
Libraries and choose
create new library and name it however you see fit.
3) Click the library you just created and choose
Include Folder, and choose the location of the new Music Folder you created in Step 1.
Tutorial: http://www.sevenforums.com/tutorials/585-library-include-folder.html?ltr=L 4) In WMP, in left panel, right click "
Music" & Choose "
Manage Music Library" set it for just My Music Directory.
This way, you can use the Library to access you Christams Music, but it will NOT be included in WMP.
If later, you want it to be, Simply follow the steps in Step 4, and include that Library as well as the "My Music" Library and all will be available.