tons on google:
http://images.google.com/images?q=nativity&hl=en&hs=aFL&lr=&client=firefox-a&rls=org.mozilla:en-US:official_s&sa=N&tab=wi&sourceid=tipimg
In case you didnt know. Right Click on image and select set as wallpaper.
http://www.google.com/search?hl=en&q=%22nativity+wallpaper%22&btnG=Google+Search
http://www.google.com/search?hl=en&q=%22nativity+graphics%22&btnG=Google+Search
Free Christian Wallpapers
http://www.appleblossomart.com/christianwalls.htm
Google nativity scene wallpaper.
oops the first time
If they are getting distorted, then it could be that Windows is stretching the image to fit the screen (this is of course only if you are using windows).
If you are and like a particular image and want to correct it, then right click on your desktop and select Properties from the pop-up menu. This will open the Display Properties window, then click on the upper tab labeled Desktop. Here you will see options for the image you have saved as your desktop on the right side. If the right side menu says Stretch, then you can set it to Center and that will remove the distortion.
tucows also has a very nice Christmas Nativity screensaver.
Christmas wallpaper ping