Customize logon screen in Windows 7

If you are interested in changing your Logon screen background, then you need to just follow the steps given below:

•  Click on the Start icon. In the search box, type regedit. Open the regedit.exe.
• You can also open regedit by typing regedit in the Run command( Windows key + R)

• In regedit,expand HKEY_LOCAL_MACHINE>>SOFTWARE>>Microsoft>>Windows>>CurrentVersion>>Authentication>>LogonUI and then click on Background.

• Double click on the OEMBackground, and change its value from 0 to 1.
• 
  •  Now,open windows explorer and navigate to : %windir%\system32\oobe (%windir% refers to location of Windows 7)
  • Create a new folder and name it info(if it does not exists). Now, create another new folder inside info and name it as backgrounds.
  • Rename the wallpaper which you want as background to backgroundDefault and place it in the background folder. (image should be a .jpg file of size less than 256KB)
  
  That’s it! Logoff and watch the changes.