Finally Microsoft has incorporated a new feature in Windows 7 which supports the end user to change the logon screen background without using any third-party tools.
In previous version of Windows, user had to use third-parry tools like Tune-Up-Utilities to change the logon screen background easily. Windows 7 now supports customization of Windows 7 logon screen officially. Replacing the old logon screen is just another task like changing wallpaper.
WARNING: This change requires a modification of the registry, and modification of the System 32 folder, both of which are essential to Windows running correctly. Be very careful while doing this hack. BACK UP YOUR DATA AND SENSTIVE FILES BEFORE PROCEEDING. I am not responsible for any data loss caused by any mishaps that may occur while performing this hack.
Step 1: Modifying the registry.
NOTE: Requires winrar to open the file. Get the program here: http://www.rarlab.com/
However, if you don't want to download anything, here is how you do it manually:
1. Press win+r (the win key is the Windows logo) and Type "Regedit" at the Run prompt.
2. Locate following registry key:
3. Now in right-side pane, change value of "OEMBackground" to 1.