Change Windows 7 logon screen
You don’t like your windows 7 logon screen? A simple procedure will ket you change the logon screen in no time.
1.     Go to start > run > type ‘regedit’ < press enter < registry editor should be open.
2.     Browse to the following registry key: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\Background
3.     Double click a DWORD key called ‘OEMBackground’ < set the decimal value to 1.
4.     Copy the picture that you want to be used as background to:
Windows \system32\oobe\info\backgrounds
Important : make sure your picture is less then 256KB and matches your screen resolution and aspect ratio.
5.     Rename the picture file you just copied to : backgroundDefault.jpg
6.     Restart your computer and you have your requested picture as logon screen.