Microsoft has released Snow Sports themepack for Windows 7 and you can now download it from the Windows Personalization Gallery.
Powder power! Catch air with the dramatic mountain skiing and snowboarding photos in this Windows 7 theme.
Download page: Microsoft.
If you wish to simply use the wallpapers, after you have applied the theme you will find them in this folder:
If you’d like to see your art on such themes, you can submit your art, photographs and creations to Windows Personalization Gallery.
Like all theme packs, these too can be used only on Windows 7 Ultimate, Home Premium, Professional, Enterprise editions, but you could extract the wallpapers if you like them and use them on your desktop. Incidentally, this theme can be used on Windows 8 too. Go here if you want to learn how to make a Windows 7 themepack.