This tool will allow you to customize the logon screen for Windows 7 without touching the registry at all. Simply download the piece of software, and make sure to Run as Administrator. Thanks to GreenMartian from Neowin for creating this tool, and djlegion from our forums for providing this nice skin.
This tool has many features that make it easy to use:
The enable option allows you to change the logon background. The disable option restores the logon background back to default with just one click.
Resize the selected image to your current resolution
Finds the highest JPG compression that would still keep it under 256kb. (Logon backgrounds cannot exceed this size)
Saves the selected image as backgroundDefault.jpg and creates a backup of the original
W7C Logon UI Changer
Windows 7 Backgrounds