How to change windows 7 welcome screen

 After booting into windows 7 you see a nice blue background in your login screen.Windows 7 allows you  to replace this bluescreen with a background of  your choice .It is as simple as changing ur wallpaper.
Step1 All you have to do is select a background of ur choice but make sure that its size is less than 256kb and it should be a jpeg file.Now rename your background  to backgroundDefault.jpg and save it in c:\windows\system32\oobe\info\backgrounds path.If the directories info & backgrounds doesn't exist dont worry.Just create a directory with name info under oobe directory.Create another subdirectory called  backgrounds under info directory.
Step 2  Open registry editor by typing the command Regedit in Run dialog box.
Navigate to the key HKEY_LOCAL_MACHINE\Microsoft\WindowsCurrentversion\Authentication\LogonUI\Background
in the left pane create a Dword called OEMBackground and assign its value to 1 .If the Dword already exists with a value 0 change its value to 1.Restart the computer its done.