Change your Win7 Log on Screen Without any Software

1. Go to RUN and type regedit and press Enter.
2. Browse to HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\Background in REGEDIT.
3. Double-click the DWORD key called OEMBackground (not there? Create it) and set its value to 1.
4. Now close REGEDIT.
5. Find the image which you want to set as log on screen and make sure its size must be less than 256 KB.
6. Copy that image to "C:\Windows\system32\oobe\info\backgrounds" . (create the info\backgrounds folders if they don't exist).
7. Rename the image to " backgroundDefault " reboot, and you should now have a custom log-on image.
8. Alternatively, you can use a free tweaking tool to handle everything for you.Logon Screen Rotator accepts multiple images and will display a different one every time you log on.