You can download a simple program called LogonStudio and change your logon screen to anything you want - a photo, a cool picture, any image. You can get this program
here. Don't worry, it's free, and you can get more logon screens
here as well.
In order to change your logon screen with this program, simply install it, then run it and double-click on the thumbnail of the image you want as your logon screen, or you can click 'Create' and create one from a pre-existing image. Logon screens you download off the site I provided can just be double-clicked and installed.
Hope I helped