I got this in a Microsoft email this morning:
Don't Miss the New Winter Fun Packs!
Download these free Fun Packs for Windows Media Player 9 Series, Windows Movie Maker 2 and Windows XP games.
I downloaded the Windows Media Player 9 Series Winter pack - which has a pretty interesting visualization that I like. I also downloaded the digital photography Winter pack (not mentioned here ... but it is there) and that has a neat screensaver changer with six real nice desktop wallpapers that change at an interval that you specify. You can also plug in your own desktop wallpaper images and override images on specific days. - I thought it was pretty cool.