/System/Library/CoreServices/SecurityAgent.app/Contents/Resources/applelogo.tifThe image can only be 90 by 90 or it will be cropped, and it must be a tif file (obviously).

/System/Library/CoreServices/loginwindow.app/Contents/Resources/MacOSX.tifYou have to reboot for the change to become evident. I used a nice image with Mr. Stupendous overlaid on the "Mac OS X" for this image.

This is my blogchalk: United States, Oklahoma, Tulsa, Midtown, English, Austin Gilbert, Male, 26-30, computer science, photography.